Fixing UI thread issues with bulk operations and request queue refactoring.

Wino.Core.Domain/Interfaces/IMailService.cs

@@ -36,6 +36,7 @@ public interface IMailService
 
     Task ChangeReadStatusAsync(string mailCopyId, bool isRead);
     Task ChangeFlagStatusAsync(string mailCopyId, bool isFlagged);
+    Task ApplyMailStateUpdatesAsync(IEnumerable<MailCopyStateUpdate> updates);
 
     Task CreateAssignmentAsync(Guid accountId, string mailCopyId, string remoteFolderId);
     Task DeleteAssignmentAsync(Guid accountId, string mailCopyId, string remoteFolderId);

Wino.Core.Domain/Models/MailItem/MailCopyStateUpdate.cs

@@ -0,0 +1,3 @@
+namespace Wino.Core.Domain.Models.MailItem;
+
+public sealed record MailCopyStateUpdate(string MailCopyId, bool? IsRead = null, bool? IsFlagged = null);

Wino.Core.Domain/Models/Requests/RequestBase.cs

@@ -44,6 +44,6 @@ public class BatchCollection<TRequestType> : List<TRequestType>, IUIChangeReques
     public BatchCollection(IEnumerable<TRequestType> collection) : base(collection)
     {
     }
-    public void ApplyUIChanges() => ForEach(x => x.ApplyUIChanges());
-    public void RevertUIChanges() => ForEach(x => x.RevertUIChanges());
+    public virtual void ApplyUIChanges() => ForEach(x => x.ApplyUIChanges());
+    public virtual void RevertUIChanges() => ForEach(x => x.RevertUIChanges());
 }

Wino.Core.Tests/Services/MailRequestStateTests.cs

@@ -27,10 +27,10 @@ public sealed class MailRequestStateTests
             request.RevertUIChanges();
 
             mailCopy.IsRead.Should().BeFalse();
-            recipient.Updated.Should().HaveCount(2);
-            recipient.Updated[0].Source.Should().Be(EntityUpdateSource.ClientUpdated);
-            recipient.Updated[1].Source.Should().Be(EntityUpdateSource.ClientReverted);
-            recipient.Updated[1].UpdatedMail.IsRead.Should().BeFalse();
+            recipient.StateUpdates.Should().HaveCount(2);
+            recipient.StateUpdates[0].Source.Should().Be(EntityUpdateSource.ClientUpdated);
+            recipient.StateUpdates[1].Source.Should().Be(EntityUpdateSource.ClientReverted);
+            recipient.StateUpdates[1].UpdatedState.IsRead.Should().BeFalse();
         }
         finally
         {
@@ -55,10 +55,10 @@ public sealed class MailRequestStateTests
             request.RevertUIChanges();
 
             mailCopy.IsFlagged.Should().BeFalse();
-            recipient.Updated.Should().HaveCount(2);
-            recipient.Updated[0].Source.Should().Be(EntityUpdateSource.ClientUpdated);
-            recipient.Updated[1].Source.Should().Be(EntityUpdateSource.ClientReverted);
-            recipient.Updated[1].UpdatedMail.IsFlagged.Should().BeFalse();
+            recipient.StateUpdates.Should().HaveCount(2);
+            recipient.StateUpdates[0].Source.Should().Be(EntityUpdateSource.ClientUpdated);
+            recipient.StateUpdates[1].Source.Should().Be(EntityUpdateSource.ClientReverted);
+            recipient.StateUpdates[1].UpdatedState.IsFlagged.Should().BeFalse();
         }
         finally
         {
@@ -76,10 +76,10 @@ public sealed class MailRequestStateTests
             IsFlagged = isFlagged
         };
 
-    internal sealed class MailRequestRecipient : IRecipient<MailUpdatedMessage>
+    internal sealed class MailRequestRecipient : IRecipient<MailStateUpdatedMessage>
     {
-        public List<MailUpdatedMessage> Updated { get; } = [];
+        public List<MailStateUpdatedMessage> StateUpdates { get; } = [];
 
-        public void Receive(MailUpdatedMessage message) => Updated.Add(message);
+        public void Receive(MailStateUpdatedMessage message) => StateUpdates.Add(message);
     }
 }

Wino.Core.Tests/Services/MailThreadingTests.cs

@@ -1,3 +1,4 @@
+using CommunityToolkit.Mvvm.Messaging;
 using FluentAssertions;
 using MimeKit;
 using Moq;
@@ -8,6 +9,7 @@ using Wino.Core.Domain.Extensions;
 using Wino.Core.Domain.Interfaces;
 using Wino.Core.Domain.Models.MailItem;
 using Wino.Core.Tests.Helpers;
+using Wino.Messaging.UI;
 using Wino.Services;
 using Xunit;
 
@@ -229,6 +231,102 @@ public class MailThreadingTests : IAsyncLifetime
         mimeMessage.ReplyTo.Mailboxes.Should().ContainSingle(m => m.Address == "support@test.local");
     }
 
+    [Fact]
+    public async Task ApplyMailStateUpdatesAsync_ForBatchReadStateChange_SendsBulkMailUpdatedMessage()
+    {
+        var mail1 = new MailCopy
+        {
+            UniqueId = Guid.NewGuid(),
+            Id = Guid.NewGuid().ToString(),
+            FolderId = _draftFolder.Id,
+            IsRead = true,
+            Subject = "First"
+        };
+        var mail2 = new MailCopy
+        {
+            UniqueId = Guid.NewGuid(),
+            Id = Guid.NewGuid().ToString(),
+            FolderId = _draftFolder.Id,
+            IsRead = true,
+            Subject = "Second"
+        };
+
+        await _databaseService.Connection.InsertAllAsync(new[] { mail1, mail2 }, typeof(MailCopy));
+
+        var recipient = new MailUpdateRecipient();
+        WeakReferenceMessenger.Default.Register<MailUpdatedMessage>(recipient);
+        WeakReferenceMessenger.Default.Register<BulkMailUpdatedMessage>(recipient);
+
+        try
+        {
+            await _mailService.ApplyMailStateUpdatesAsync(
+            [
+                new MailCopyStateUpdate(mail1.Id, IsRead: false),
+                new MailCopyStateUpdate(mail2.Id, IsRead: false)
+            ]);
+
+            recipient.SingleUpdates.Should().BeEmpty();
+            recipient.BulkUpdates.Should().ContainSingle();
+            recipient.BulkUpdates[0].Source.Should().Be(EntityUpdateSource.Server);
+            recipient.BulkUpdates[0].ChangedProperties.Should().Be(MailCopyChangeFlags.IsRead);
+            recipient.BulkUpdates[0].UpdatedMails.Should().HaveCount(2);
+            recipient.BulkUpdates[0].UpdatedMails.Should().OnlyContain(x => !x.IsRead);
+
+            (await _databaseService.Connection.FindAsync<MailCopy>(mail1.UniqueId))!.IsRead.Should().BeFalse();
+            (await _databaseService.Connection.FindAsync<MailCopy>(mail2.UniqueId))!.IsRead.Should().BeFalse();
+        }
+        finally
+        {
+            WeakReferenceMessenger.Default.Unregister<MailUpdatedMessage>(recipient);
+            WeakReferenceMessenger.Default.Unregister<BulkMailUpdatedMessage>(recipient);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyMailStateUpdatesAsync_ForBatchMarkRead_SendsBulkMailReadStatusChanged()
+    {
+        var mail1 = new MailCopy
+        {
+            UniqueId = Guid.NewGuid(),
+            Id = Guid.NewGuid().ToString(),
+            FolderId = _draftFolder.Id,
+            IsRead = false,
+            Subject = "First unread"
+        };
+        var mail2 = new MailCopy
+        {
+            UniqueId = Guid.NewGuid(),
+            Id = Guid.NewGuid().ToString(),
+            FolderId = _draftFolder.Id,
+            IsRead = false,
+            Subject = "Second unread"
+        };
+
+        await _databaseService.Connection.InsertAllAsync(new[] { mail1, mail2 }, typeof(MailCopy));
+
+        var recipient = new MailReadStatusRecipient();
+        WeakReferenceMessenger.Default.Register<MailReadStatusChanged>(recipient);
+        WeakReferenceMessenger.Default.Register<BulkMailReadStatusChanged>(recipient);
+
+        try
+        {
+            await _mailService.ApplyMailStateUpdatesAsync(
+            [
+                new MailCopyStateUpdate(mail1.Id, IsRead: true),
+                new MailCopyStateUpdate(mail2.Id, IsRead: true)
+            ]);
+
+            recipient.SingleUpdates.Should().BeEmpty();
+            recipient.BulkUpdates.Should().ContainSingle();
+            recipient.BulkUpdates[0].UniqueIds.Should().BeEquivalentTo([mail1.UniqueId, mail2.UniqueId]);
+        }
+        finally
+        {
+            WeakReferenceMessenger.Default.Unregister<MailReadStatusChanged>(recipient);
+            WeakReferenceMessenger.Default.Unregister<BulkMailReadStatusChanged>(recipient);
+        }
+    }
+
     private static MimeMessage CreateReferencedMimeMessage(string subject, string? messageId = null)
     {
         var message = new MimeMessage();
@@ -243,6 +341,24 @@ public class MailThreadingTests : IAsyncLifetime
         return message;
     }
 
+    internal sealed class MailUpdateRecipient : IRecipient<MailUpdatedMessage>, IRecipient<BulkMailUpdatedMessage>
+    {
+        public List<MailUpdatedMessage> SingleUpdates { get; } = [];
+        public List<BulkMailUpdatedMessage> BulkUpdates { get; } = [];
+
+        public void Receive(MailUpdatedMessage message) => SingleUpdates.Add(message);
+        public void Receive(BulkMailUpdatedMessage message) => BulkUpdates.Add(message);
+    }
+
+    internal sealed class MailReadStatusRecipient : IRecipient<MailReadStatusChanged>, IRecipient<BulkMailReadStatusChanged>
+    {
+        public List<MailReadStatusChanged> SingleUpdates { get; } = [];
+        public List<BulkMailReadStatusChanged> BulkUpdates { get; } = [];
+
+        public void Receive(MailReadStatusChanged message) => SingleUpdates.Add(message);
+        public void Receive(BulkMailReadStatusChanged message) => BulkUpdates.Add(message);
+    }
+
     private static MailService BuildMailService(InMemoryDatabaseService db)
     {
         var signatureService = new Mock<ISignatureService>();

Wino.Core.Tests/Synchronizers/BaseSynchronizerUiChangeTests.cs

@@ -0,0 +1,84 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using CommunityToolkit.Mvvm.Messaging;
+using FluentAssertions;
+using Wino.Core.Domain.Entities.Mail;
+using Wino.Core.Domain.Entities.Shared;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Interfaces;
+using Wino.Core.Requests.Bundles;
+using Wino.Core.Requests.Mail;
+using Wino.Core.Synchronizers;
+using Wino.Messaging.UI;
+using Xunit;
+
+namespace Wino.Core.Tests.Synchronizers;
+
+public sealed class BaseSynchronizerUiChangeTests
+{
+    [Fact]
+    public void ApplyOptimisticUiChanges_UsesBundleUiChangeRequest_ForBatchBundle()
+    {
+        var folderId = Guid.NewGuid();
+        var account = new MailAccount { Id = Guid.NewGuid(), Name = "Test account" };
+        var synchronizer = new TestSynchronizer(account);
+        var recipient = new UiChangeRecipient();
+
+        var request1 = new MarkReadRequest(CreateMailCopy(folderId, isRead: false), IsRead: true);
+        var request2 = new MarkReadRequest(CreateMailCopy(folderId, isRead: false), IsRead: true);
+        var batchRequest = new BatchMarkReadRequest([request1, request2]);
+        var bundle = new HttpRequestBundle<object>(new object(), batchRequest, request1);
+
+        WeakReferenceMessenger.Default.Register<MailStateUpdatedMessage>(recipient);
+        WeakReferenceMessenger.Default.Register<BulkMailStateUpdatedMessage>(recipient);
+
+        try
+        {
+            synchronizer.ApplyUiChanges([bundle]);
+
+            recipient.SingleUpdates.Should().BeEmpty();
+            recipient.BulkUpdates.Should().ContainSingle();
+            recipient.BulkUpdates[0].UpdatedStates.Should().HaveCount(2);
+            request1.Item.IsRead.Should().BeFalse();
+            request2.Item.IsRead.Should().BeFalse();
+        }
+        finally
+        {
+            WeakReferenceMessenger.Default.Unregister<MailStateUpdatedMessage>(recipient);
+            WeakReferenceMessenger.Default.Unregister<BulkMailStateUpdatedMessage>(recipient);
+        }
+    }
+
+    private static MailCopy CreateMailCopy(Guid folderId, bool isRead) =>
+        new()
+        {
+            UniqueId = Guid.NewGuid(),
+            Id = Guid.NewGuid().ToString(),
+            FolderId = folderId,
+            IsRead = isRead
+        };
+
+    private sealed class TestSynchronizer : BaseSynchronizer<object>
+    {
+        public TestSynchronizer(MailAccount account)
+            : base(account, WeakReferenceMessenger.Default)
+        {
+        }
+
+        public void ApplyUiChanges(List<IRequestBundle<object>> bundles) => ApplyOptimisticUiChanges(bundles);
+
+        public override Task ExecuteNativeRequestsAsync(List<IRequestBundle<object>> batchedRequests, CancellationToken cancellationToken = default)
+            => Task.CompletedTask;
+    }
+
+    internal sealed class UiChangeRecipient : IRecipient<MailStateUpdatedMessage>, IRecipient<BulkMailStateUpdatedMessage>
+    {
+        public List<MailStateUpdatedMessage> SingleUpdates { get; } = [];
+        public List<BulkMailStateUpdatedMessage> BulkUpdates { get; } = [];
+
+        public void Receive(MailStateUpdatedMessage message) => SingleUpdates.Add(message);
+        public void Receive(BulkMailStateUpdatedMessage message) => BulkUpdates.Add(message);
+    }
+}

Wino.Core.Tests/Synchronizers/UnifiedImapSynchronizerTests.cs

@@ -2,12 +2,14 @@ using FluentAssertions;
 using MailKit;
 using MailKit.Net.Imap;
 using Moq;
+using System.Linq;
 using System.Reflection;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Entities.Shared;
 using Wino.Core.Domain.Interfaces;
 using Wino.Core.Domain.Models.MailItem;
 using Wino.Core.Synchronizers.ImapSync;
+using Wino.Services.Extensions;
 using Xunit;
 using IMailService = Wino.Core.Domain.Interfaces.IMailService;
 
@@ -223,4 +225,61 @@ public class UnifiedImapSynchronizerTests
         capturedPackage.Should().NotBeNull();
         capturedPackage!.MimeMessage.Should().BeNull();
     }
+
+    [Fact]
+    public async Task ProcessSummariesAsync_ShouldBatchStateUpdates_ForExistingMailCopies()
+    {
+        var localFolder = new MailItemFolder
+        {
+            Id = Guid.NewGuid(),
+            MailAccountId = Guid.NewGuid(),
+            FolderName = "Inbox",
+            RemoteFolderId = "INBOX"
+        };
+
+        var summaryMock = new Mock<IMessageSummary>();
+        summaryMock.SetupGet(x => x.UniqueId).Returns(new UniqueId(42));
+        summaryMock.SetupGet(x => x.Flags).Returns(MessageFlags.Seen | MessageFlags.Flagged);
+
+        var existingMailCopy = new MailCopy
+        {
+            Id = MailkitClientExtensions.CreateUid(localFolder.Id, 42),
+            IsRead = false,
+            IsFlagged = false
+        };
+
+        var mailServiceMock = new Mock<IMailService>();
+        mailServiceMock
+            .Setup(x => x.GetExistingMailsAsync(localFolder.Id, It.IsAny<IEnumerable<UniqueId>>()))
+            .ReturnsAsync([existingMailCopy]);
+        mailServiceMock
+            .Setup(x => x.ApplyMailStateUpdatesAsync(It.IsAny<IEnumerable<MailCopyStateUpdate>>()))
+            .Returns(Task.CompletedTask);
+
+        var sut = new UnifiedImapSynchronizer(
+            Mock.Of<IFolderService>(),
+            mailServiceMock.Object,
+            Mock.Of<IImapSynchronizerErrorHandlerFactory>());
+
+        var imapSynchronizerMock = new Mock<IImapSynchronizer>();
+
+        var processMethod = typeof(UnifiedImapSynchronizer).GetMethod("ProcessSummariesAsync", BindingFlags.Instance | BindingFlags.NonPublic);
+        processMethod.Should().NotBeNull();
+
+        var task = (Task<List<string>>)processMethod!.Invoke(
+            sut,
+            [imapSynchronizerMock.Object, localFolder, new List<IMessageSummary> { summaryMock.Object }, CancellationToken.None])!;
+
+        var result = await task;
+
+        result.Should().BeEmpty();
+        mailServiceMock.Verify(
+            x => x.ApplyMailStateUpdatesAsync(It.Is<IEnumerable<MailCopyStateUpdate>>(updates =>
+                updates.Count() == 1
+                && updates.First().MailCopyId == existingMailCopy.Id
+                && updates.First().IsRead == true
+                && updates.First().IsFlagged == true)),
+            Times.Once);
+        mailServiceMock.Verify(x => x.CreateMailAsync(It.IsAny<Guid>(), It.IsAny<NewMailItemPackage>()), Times.Never);
+    }
 }

Wino.Core.Tests/Synchronizers/WinoSynchronizerMailRequestTests.cs

@@ -10,6 +10,7 @@ using Wino.Core.Domain.Enums;
 using Wino.Core.Domain.Interfaces;
 using Wino.Core.Domain.Models.MailItem;
 using Wino.Core.Domain.Models.Synchronization;
+using Wino.Core.Requests.Mail;
 using Wino.Core.Requests.Folder;
 using Wino.Core.Synchronizers;
 using Xunit;
@@ -49,6 +50,38 @@ public sealed class WinoSynchronizerMailRequestTests
         synchronizer.ExecuteNativeRequestsInvocationCount.Should().Be(1);
     }
 
+    [Fact]
+    public async Task ExecuteRequests_should_dispatch_grouped_mark_read_requests_with_composite_grouping_key()
+    {
+        var synchronizer = new TestMailSynchronizer();
+        var folderId = Guid.NewGuid();
+
+        synchronizer.QueueRequest(new MarkReadRequest(new MailCopy
+        {
+            UniqueId = Guid.NewGuid(),
+            Id = Guid.NewGuid().ToString(),
+            FolderId = folderId
+        }, IsRead: true));
+
+        synchronizer.QueueRequest(new MarkReadRequest(new MailCopy
+        {
+            UniqueId = Guid.NewGuid(),
+            Id = Guid.NewGuid().ToString(),
+            FolderId = folderId
+        }, IsRead: true));
+
+        var result = await synchronizer.SynchronizeMailsAsync(new MailSynchronizationOptions
+        {
+            AccountId = synchronizer.Account.Id,
+            Type = MailSynchronizationType.ExecuteRequests
+        });
+
+        result.CompletedState.Should().Be(SynchronizationCompletedState.Success);
+        synchronizer.MarkReadInvocationCount.Should().Be(1);
+        synchronizer.LastMarkReadBatchCount.Should().Be(2);
+        synchronizer.ExecuteNativeRequestsInvocationCount.Should().Be(1);
+    }
+
     private sealed class TestMailSynchronizer
         : WinoSynchronizer<object, object, object>
     {
@@ -60,6 +93,8 @@ public sealed class WinoSynchronizerMailRequestTests
         public override uint BatchModificationSize => 1;
         public override uint InitialMessageDownloadCountPerFolder => 0;
         public int CreateRootFolderInvocationCount { get; private set; }
+        public int MarkReadInvocationCount { get; private set; }
+        public int LastMarkReadBatchCount { get; private set; }
         public int ExecuteNativeRequestsInvocationCount { get; private set; }
 
         public override List<IRequestBundle<object>> CreateRootFolder(CreateRootFolderRequest request)
@@ -68,6 +103,13 @@ public sealed class WinoSynchronizerMailRequestTests
             return [new TestRequestBundle(new object(), request)];
         }
 
+        public override List<IRequestBundle<object>> MarkRead(BatchMarkReadRequest request)
+        {
+            MarkReadInvocationCount++;
+            LastMarkReadBatchCount = request.Count;
+            return [new TestRequestBundle(new object(), request[0])];
+        }
+
         public override Task ExecuteNativeRequestsAsync(List<IRequestBundle<object>> batchedRequests, CancellationToken cancellationToken = default)
         {
             ExecuteNativeRequestsInvocationCount++;

Wino.Core/Requests/Folder/EmptyFolderRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -14,18 +15,26 @@ public record EmptyFolderRequest(MailItemFolder Folder, List<MailCopy> MailsToDe
     public bool ExcludeMustHaveFolders => false;
     public override void ApplyUIChanges()
     {
-        foreach (var item in MailsToDelete)
-        {
-            WeakReferenceMessenger.Default.Send(new MailRemovedMessage(item, EntityUpdateSource.ClientUpdated));
-        }
+        var removedMails = MailsToDelete?
+            .Where(item => item != null)
+            .ToList();
+
+        if (removedMails == null || removedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailRemovedMessage(removedMails, EntityUpdateSource.ClientUpdated));
     }
 
     public override void RevertUIChanges()
     {
-        foreach (var item in MailsToDelete)
-        {
-            WeakReferenceMessenger.Default.Send(new MailAddedMessage(item, EntityUpdateSource.ClientReverted));
-        }
+        var addedMails = MailsToDelete?
+            .Where(item => item != null)
+            .ToList();
+
+        if (addedMails == null || addedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailAddedMessage(addedMails, EntityUpdateSource.ClientReverted));
     }
 
     public List<Guid> SynchronizationFolderIds => [Folder.Id];

Wino.Core/Requests/Folder/MarkFolderAsReadRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -17,31 +18,31 @@ public record MarkFolderAsReadRequest(MailItemFolder Folder, List<MailCopy> Mail
 
     public override void ApplyUIChanges()
     {
-        if (MailsToMarkRead == null || MailsToMarkRead.Count == 0) return;
+        var updatedMails = MailsToMarkRead?
+            .Where(item => item != null && !item.IsRead)
+            .Select(item => new MailStateChange(item.UniqueId, IsRead: true))
+            .ToList();
 
-        foreach (var item in MailsToMarkRead)
-        {
-            // Skip if already read
-            if (item.IsRead) continue;
+        if (updatedMails == null || updatedMails.Count == 0)
+            return;
 
-            item.IsRead = true;
-
-            WeakReferenceMessenger.Default.Send(new MailUpdatedMessage(item, EntityUpdateSource.ClientUpdated, MailCopyChangeFlags.IsRead));
-        }
+        WeakReferenceMessenger.Default.Send(new BulkMailStateUpdatedMessage(
+            updatedMails,
+            EntityUpdateSource.ClientUpdated));
     }
 
     public override void RevertUIChanges()
     {
-        if (MailsToMarkRead == null || MailsToMarkRead.Count == 0) return;
+        var updatedMails = MailsToMarkRead?
+            .Where(item => item != null && !item.IsRead)
+            .Select(item => new MailStateChange(item.UniqueId, IsRead: false))
+            .ToList();
 
-        foreach (var item in MailsToMarkRead)
-        {
-            // Skip if already unread (wasn't changed by ApplyUIChanges)
-            if (!item.IsRead) continue;
+        if (updatedMails == null || updatedMails.Count == 0)
+            return;
 
-            item.IsRead = false;
-
-            WeakReferenceMessenger.Default.Send(new MailUpdatedMessage(item, EntityUpdateSource.ClientReverted, MailCopyChangeFlags.IsRead));
-        }
+        WeakReferenceMessenger.Default.Send(new BulkMailStateUpdatedMessage(
+            updatedMails,
+            EntityUpdateSource.ClientReverted));
     }
 }

Wino.Core/Requests/Mail/ArchiveRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -38,6 +39,7 @@ public record ArchiveRequest(bool IsArchiving, MailCopy Item, MailItemFolder Fro
     }
 
     public override MailSynchronizerOperation Operation => MailSynchronizerOperation.Archive;
+    public override object GroupingKey() => (Operation, IsArchiving, FromFolder.Id, ToFolder?.Id ?? Guid.Empty);
 
     public override void ApplyUIChanges()
     {
@@ -55,4 +57,22 @@ public class BatchArchiveRequest : BatchCollection<ArchiveRequest>
     public BatchArchiveRequest(IEnumerable<ArchiveRequest> collection) : base(collection)
     {
     }
+
+    public override void ApplyUIChanges()
+    {
+        var removedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (removedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailRemovedMessage(removedMails, EntityUpdateSource.ClientUpdated));
+    }
+
+    public override void RevertUIChanges()
+    {
+        var addedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (addedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailAddedMessage(addedMails, EntityUpdateSource.ClientReverted));
+    }
 }

Wino.Core/Requests/Mail/ChangeFlagRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -25,25 +26,26 @@ public record ChangeFlagRequest(MailCopy Item, bool IsFlagged) : MailRequestBase
     /// If the mail is already in the desired flagged state, no change is needed.
     /// </summary>
     public bool IsNoOp { get; } = Item.IsFlagged == IsFlagged;
+    public bool OriginalIsFlagged => _originalIsFlagged;
+
+    public override object GroupingKey() => (Operation, Item.FolderId, IsFlagged);
 
     public override void ApplyUIChanges()
     {
-        // Skip UI update if the mail is already in the desired state
         if (IsNoOp) return;
 
-        Item.IsFlagged = IsFlagged;
-
-        WeakReferenceMessenger.Default.Send(new MailUpdatedMessage(Item, EntityUpdateSource.ClientUpdated, MailCopyChangeFlags.IsFlagged));
+        WeakReferenceMessenger.Default.Send(new MailStateUpdatedMessage(
+            new MailStateChange(Item.UniqueId, IsFlagged: IsFlagged),
+            EntityUpdateSource.ClientUpdated));
     }
 
     public override void RevertUIChanges()
     {
-        // Skip UI revert if this was a no-op request
         if (IsNoOp) return;
 
-        Item.IsFlagged = _originalIsFlagged;
-
-        WeakReferenceMessenger.Default.Send(new MailUpdatedMessage(Item, EntityUpdateSource.ClientReverted, MailCopyChangeFlags.IsFlagged));
+        WeakReferenceMessenger.Default.Send(new MailStateUpdatedMessage(
+            new MailStateChange(Item.UniqueId, IsFlagged: _originalIsFlagged),
+            EntityUpdateSource.ClientReverted));
     }
 }
 
@@ -52,4 +54,34 @@ public class BatchChangeFlagRequest : BatchCollection<ChangeFlagRequest>
     public BatchChangeFlagRequest(IEnumerable<ChangeFlagRequest> collection) : base(collection)
     {
     }
+
+    public override void ApplyUIChanges()
+    {
+        var updatedMails = this
+            .Where(x => !x.IsNoOp)
+            .Select(x => new MailStateChange(x.Item.UniqueId, IsFlagged: x.IsFlagged))
+            .ToList();
+
+        if (updatedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailStateUpdatedMessage(
+            updatedMails,
+            EntityUpdateSource.ClientUpdated));
+    }
+
+    public override void RevertUIChanges()
+    {
+        var updatedMails = this
+            .Where(x => !x.IsNoOp)
+            .Select(x => new MailStateChange(x.Item.UniqueId, IsFlagged: x.OriginalIsFlagged))
+            .ToList();
+
+        if (updatedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailStateUpdatedMessage(
+            updatedMails,
+            EntityUpdateSource.ClientReverted));
+    }
 }

Wino.Core/Requests/Mail/ChangeJunkStateRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -30,6 +31,7 @@ public record ChangeJunkStateRequest(bool IsJunk, MailCopy Item, MailItemFolder
     public bool ExcludeMustHaveFolders => false;
 
     public override MailSynchronizerOperation Operation => MailSynchronizerOperation.ChangeJunkState;
+    public override object GroupingKey() => (Operation, IsJunk, FromFolder.Id, TargetFolder?.Id ?? Guid.Empty);
 
     public override void ApplyUIChanges()
     {
@@ -47,4 +49,22 @@ public class BatchChangeJunkStateRequest : BatchCollection<ChangeJunkStateReques
     public BatchChangeJunkStateRequest(IEnumerable<ChangeJunkStateRequest> collection) : base(collection)
     {
     }
+
+    public override void ApplyUIChanges()
+    {
+        var removedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (removedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailRemovedMessage(removedMails, EntityUpdateSource.ClientUpdated));
+    }
+
+    public override void RevertUIChanges()
+    {
+        var addedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (addedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailAddedMessage(addedMails, EntityUpdateSource.ClientReverted));
+    }
 }

Wino.Core/Requests/Mail/DeleteRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -19,6 +20,7 @@ public record DeleteRequest(MailCopy MailItem) : MailRequestBase(MailItem),
     public List<Guid> SynchronizationFolderIds => [Item.FolderId];
     public bool ExcludeMustHaveFolders => false;
     public override MailSynchronizerOperation Operation => MailSynchronizerOperation.Delete;
+    public override object GroupingKey() => (Operation, Item.FolderId);
 
     public override void ApplyUIChanges()
     {
@@ -36,4 +38,22 @@ public class BatchDeleteRequest : BatchCollection<DeleteRequest>
     public BatchDeleteRequest(IEnumerable<DeleteRequest> collection) : base(collection)
     {
     }
+
+    public override void ApplyUIChanges()
+    {
+        var removedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (removedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailRemovedMessage(removedMails, EntityUpdateSource.ClientUpdated));
+    }
+
+    public override void RevertUIChanges()
+    {
+        var addedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (addedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailAddedMessage(addedMails, EntityUpdateSource.ClientReverted));
+    }
 }

Wino.Core/Requests/Mail/MarkReadRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -24,25 +25,26 @@ public record MarkReadRequest(MailCopy Item, bool IsRead) : MailRequestBase(Item
     /// If the mail is already in the desired read state, no change is needed.
     /// </summary>
     public bool IsNoOp { get; } = Item.IsRead == IsRead;
+    public bool OriginalIsRead => _originalIsRead;
+
+    public override object GroupingKey() => (Operation, Item.FolderId, IsRead);
 
     public override void ApplyUIChanges()
     {
-        // Skip UI update if the mail is already in the desired state
         if (IsNoOp) return;
 
-        Item.IsRead = IsRead;
-
-        WeakReferenceMessenger.Default.Send(new MailUpdatedMessage(Item, EntityUpdateSource.ClientUpdated, MailCopyChangeFlags.IsRead));
+        WeakReferenceMessenger.Default.Send(new MailStateUpdatedMessage(
+            new MailStateChange(Item.UniqueId, IsRead: IsRead),
+            EntityUpdateSource.ClientUpdated));
     }
 
     public override void RevertUIChanges()
     {
-        // Skip UI revert if this was a no-op request
         if (IsNoOp) return;
 
-        Item.IsRead = _originalIsRead;
-
-        WeakReferenceMessenger.Default.Send(new MailUpdatedMessage(Item, EntityUpdateSource.ClientReverted, MailCopyChangeFlags.IsRead));
+        WeakReferenceMessenger.Default.Send(new MailStateUpdatedMessage(
+            new MailStateChange(Item.UniqueId, IsRead: _originalIsRead),
+            EntityUpdateSource.ClientReverted));
     }
 }
 
@@ -51,4 +53,34 @@ public class BatchMarkReadRequest : BatchCollection<MarkReadRequest>
     public BatchMarkReadRequest(IEnumerable<MarkReadRequest> collection) : base(collection)
     {
     }
+
+    public override void ApplyUIChanges()
+    {
+        var updatedMails = this
+            .Where(x => !x.IsNoOp)
+            .Select(x => new MailStateChange(x.Item.UniqueId, IsRead: x.IsRead))
+            .ToList();
+
+        if (updatedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailStateUpdatedMessage(
+            updatedMails,
+            EntityUpdateSource.ClientUpdated));
+    }
+
+    public override void RevertUIChanges()
+    {
+        var updatedMails = this
+            .Where(x => !x.IsNoOp)
+            .Select(x => new MailStateChange(x.Item.UniqueId, IsRead: x.OriginalIsRead))
+            .ToList();
+
+        if (updatedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailStateUpdatedMessage(
+            updatedMails,
+            EntityUpdateSource.ClientReverted));
+    }
 }

Wino.Core/Requests/Mail/MoveRequest.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using CommunityToolkit.Mvvm.Messaging;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Enums;
@@ -15,6 +16,7 @@ public record MoveRequest(MailCopy Item, MailItemFolder FromFolder, MailItemFold
     public List<Guid> SynchronizationFolderIds => new() { FromFolder.Id, ToFolder.Id };
     public bool ExcludeMustHaveFolders => false;
     public override MailSynchronizerOperation Operation => MailSynchronizerOperation.Move;
+    public override object GroupingKey() => (Operation, FromFolder.Id, ToFolder?.Id ?? Guid.Empty);
 
     public override void ApplyUIChanges()
     {
@@ -32,4 +34,22 @@ public class BatchMoveRequest : BatchCollection<MoveRequest>, IUIChangeRequest
     public BatchMoveRequest(IEnumerable<MoveRequest> collection) : base(collection)
     {
     }
+
+    public override void ApplyUIChanges()
+    {
+        var removedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (removedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailRemovedMessage(removedMails, EntityUpdateSource.ClientUpdated));
+    }
+
+    public override void RevertUIChanges()
+    {
+        var addedMails = this.Select(x => x.Item).Where(x => x != null).ToList();
+        if (addedMails.Count == 0)
+            return;
+
+        WeakReferenceMessenger.Default.Send(new BulkMailAddedMessage(addedMails, EntityUpdateSource.ClientReverted));
+    }
 }

Wino.Core/Services/SynchronizationManager.cs

@@ -259,25 +259,48 @@ public class SynchronizationManager : ISynchronizationManager, IRecipient<Accoun
     /// <param name="accountId">Account ID to queue the request for</param>
     /// <param name="triggerSynchronization">Whether to automatically trigger synchronization after queuing the request</param>
     public async Task QueueRequestAsync(IRequestBase request, Guid accountId, bool triggerSynchronization)
+        => await QueueRequestsAsync([request], accountId, triggerSynchronization).ConfigureAwait(false);
+
+    public async Task QueueRequestsAsync(IEnumerable<IRequestBase> requests, Guid accountId, bool triggerSynchronization)
     {
         EnsureInitialized();
 
+        var requestList = requests?.Where(request => request != null).ToList() ?? [];
+        if (requestList.Count == 0)
+            return;
+
         var synchronizer = await GetOrCreateSynchronizerAsync(accountId);
         if (synchronizer == null)
         {
-            _logger.Error("Could not find or create synchronizer for account {AccountId} to queue request", accountId);
+            _logger.Error("Could not find or create synchronizer for account {AccountId} to queue {RequestCount} request(s)", accountId, requestList.Count);
             return;
         }
 
-        _logger.Debug("Queuing request {RequestType} for account {AccountId}",
-                     request.GetType().Name, accountId);
+        if (requestList.Count == 1)
+        {
+            _logger.Debug("Queuing request {RequestType} for account {AccountId}",
+                         requestList[0].GetType().Name, accountId);
+        }
+        else
+        {
+            var requestSummary = string.Join(", ", requestList
+                .GroupBy(request => request.GetType().Name)
+                .OrderBy(group => group.Key)
+                .Select(group => $"{group.Key} x{group.Count()}"));
 
-        synchronizer.QueueRequest(request);
+            _logger.Debug("Queuing {RequestCount} requests for account {AccountId}: {RequestSummary}",
+                         requestList.Count, accountId, requestSummary);
+        }
+
+        foreach (var request in requestList)
+        {
+            synchronizer.QueueRequest(request);
+        }
 
         if (triggerSynchronization)
         {
             // Determine if this is a calendar or mail operation
-            bool isCalendarOperation = request is ICalendarActionRequest;
+            bool isCalendarOperation = requestList.All(request => request is ICalendarActionRequest);
 
             if (isCalendarOperation)
             {

Wino.Core/Services/WinoRequestDelegator.cs

@@ -93,13 +93,11 @@ public class WinoRequestDelegator : IWinoRequestDelegator
         // Queue requests for each account and start synchronization.
         foreach (var accountGroup in accountIds)
         {
-            foreach (var accountRequest in accountGroup)
-            {
-                await QueueRequestAsync(accountRequest, accountGroup.Key);
-            }
+            var groupedRequests = accountGroup.Cast<IRequestBase>().ToList();
+            await QueueRequestsAsync(groupedRequests, accountGroup.Key).ConfigureAwait(false);
 
             var account = accountGroup.First().Item.AssignedAccount;
-            var actionItems = SynchronizationActionHelper.CreateActionItems(accountGroup, accountGroup.Key, account.Name);
+            var actionItems = SynchronizationActionHelper.CreateActionItems(groupedRequests, accountGroup.Key, account.Name);
 
             if (actionItems.Count > 0)
                 WeakReferenceMessenger.Default.Send(new SynchronizationActionsAdded(accountGroup.Key, account.Name, actionItems));
@@ -214,10 +212,7 @@ public class WinoRequestDelegator : IWinoRequestDelegator
         if (requestList.Count == 0)
             return;
 
-        foreach (var request in requestList)
-        {
-            await QueueRequestAsync(request, accountId).ConfigureAwait(false);
-        }
+        await QueueRequestsAsync(requestList, accountId).ConfigureAwait(false);
 
         await SendSyncActionsAddedAsync(requestList, accountId).ConfigureAwait(false);
         await QueueSynchronizationAsync(accountId).ConfigureAwait(false);
@@ -274,7 +269,12 @@ public class WinoRequestDelegator : IWinoRequestDelegator
     private async Task QueueRequestAsync(IRequestBase request, Guid accountId)
     {
         // Don't trigger synchronization for individual requests - we'll trigger it once for all requests
-        await SynchronizationManager.Instance.QueueRequestAsync(request, accountId, triggerSynchronization: false);
+        await SynchronizationManager.Instance.QueueRequestAsync(request, accountId, triggerSynchronization: false).ConfigureAwait(false);
+    }
+
+    private async Task QueueRequestsAsync(IEnumerable<IRequestBase> requests, Guid accountId)
+    {
+        await SynchronizationManager.Instance.QueueRequestsAsync(requests, accountId, triggerSynchronization: false).ConfigureAwait(false);
     }
 
     private Task QueueSynchronizationAsync(Guid accountId)

Wino.Core/Services/WinoRequestProcessor.cs

@@ -54,6 +54,10 @@ public class WinoRequestProcessor : IWinoRequestProcessor
     {
         var action = preperationRequest.Action;
         var moveTargetStructure = preperationRequest.MoveTargetFolder;
+        var mailItems = preperationRequest.MailItems?.Where(item => item != null).ToList() ?? [];
+
+        if (mailItems.Count == 0)
+            return [];
 
         // Ask confirmation for permanent delete operation.
         // Drafts are always hard deleted without any protection.
@@ -78,12 +82,12 @@ public class WinoRequestProcessor : IWinoRequestProcessor
             // Handle the case when user is trying to move multiple mails that belong to different accounts.
             // We can't handle this with only 1 picker dialog.
 
-            bool isInvalidMoveTarget = preperationRequest.MailItems.Select(a => a.AssignedAccount.Id).Distinct().Count() > 1;
+            bool isInvalidMoveTarget = mailItems.Select(a => a.AssignedAccount.Id).Distinct().Count() > 1;
 
             if (isInvalidMoveTarget)
                 throw new InvalidMoveTargetException(InvalidMoveTargetReason.MultipleAccounts);
 
-            var accountId = preperationRequest.MailItems.FirstOrDefault().AssignedAccount.Id;
+            var accountId = mailItems[0].AssignedAccount.Id;
 
             moveTargetStructure = await _dialogService.PickFolderAsync(accountId, PickFolderReason.Move, _folderService);
 
@@ -94,7 +98,7 @@ public class WinoRequestProcessor : IWinoRequestProcessor
         var requests = new List<IMailActionRequest>();
 
         // TODO: Fix: Collection was modified; enumeration operation may not execute
-        foreach (var item in preperationRequest.MailItems.ToList())
+        foreach (var item in mailItems)
         {
             var singleRequest = await GetSingleRequestAsync(item, action, moveTargetStructure, preperationRequest.ToggleExecution);
 

Wino.Core/Synchronizers/BaseSynchronizer.cs

@@ -12,6 +12,7 @@ using Wino.Core.Domain.Enums;
 using Wino.Core.Domain.Interfaces;
 using Wino.Core.Domain.Models.Accounts;
 using Wino.Core.Domain.Models.Synchronization;
+using Wino.Core.Requests.Mail;
 using Wino.Core.Requests.Bundles;
 using Wino.Messaging.UI;
 
@@ -262,4 +263,75 @@ public abstract partial class BaseSynchronizer<TBaseRequest> : ObservableObject,
 
         return ret;
     }
+
+    protected void ApplyOptimisticUiChanges(IEnumerable<IRequestBundle<TBaseRequest>> bundles, Func<IRequestBase, bool> shouldApply = null)
+    {
+        var bundleList = bundles?
+            .Where(b => b?.Request != null && (shouldApply?.Invoke(b.Request) ?? true))
+            .ToList() ?? [];
+
+        if (bundleList.Count == 0)
+            return;
+
+        var requestList = new List<IRequestBase>(bundleList.Count);
+
+        foreach (var bundle in bundleList)
+        {
+            if (bundle.UIChangeRequest != null && !ReferenceEquals(bundle.UIChangeRequest, bundle.Request))
+            {
+                bundle.UIChangeRequest.ApplyUIChanges();
+                continue;
+            }
+
+            requestList.Add(bundle.Request);
+        }
+
+        if (requestList.Count == 0)
+            return;
+
+        var appliedBatchRequestKeys = new HashSet<object>();
+
+        foreach (var group in requestList.GroupBy(r => r.GroupingKey()))
+        {
+            var groupRequests = group.ToList();
+            if (groupRequests.Count <= 1)
+                continue;
+
+            if (!TryApplyBatchUiChanges(groupRequests))
+                continue;
+
+            appliedBatchRequestKeys.Add(group.Key);
+        }
+
+        foreach (var request in requestList)
+        {
+            if (!appliedBatchRequestKeys.Contains(request.GroupingKey()))
+            {
+                request.ApplyUIChanges();
+            }
+        }
+    }
+
+    private static bool TryApplyBatchUiChanges(IReadOnlyList<IRequestBase> requests)
+    {
+        if (requests == null || requests.Count <= 1)
+            return false;
+
+        return requests[0] switch
+        {
+            MarkReadRequest => ApplyBatch(new BatchMarkReadRequest(requests.Cast<MarkReadRequest>())),
+            ChangeFlagRequest => ApplyBatch(new BatchChangeFlagRequest(requests.Cast<ChangeFlagRequest>())),
+            DeleteRequest => ApplyBatch(new BatchDeleteRequest(requests.Cast<DeleteRequest>())),
+            MoveRequest => ApplyBatch(new BatchMoveRequest(requests.Cast<MoveRequest>())),
+            ArchiveRequest => ApplyBatch(new BatchArchiveRequest(requests.Cast<ArchiveRequest>())),
+            ChangeJunkStateRequest => ApplyBatch(new BatchChangeJunkStateRequest(requests.Cast<ChangeJunkStateRequest>())),
+            _ => false
+        };
+
+        static bool ApplyBatch(IUIChangeRequest request)
+        {
+            request.ApplyUIChanges();
+            return true;
+        }
+    }
 }

Wino.Core/Synchronizers/ImapSync/UnifiedImapSynchronizer.cs

@@ -29,6 +29,8 @@ namespace Wino.Core.Synchronizers.ImapSync;
 public class UnifiedImapSynchronizer
 {
     private static readonly TimeSpan UidReconcileInterval = TimeSpan.FromHours(12);
+    private const int NewMessageFetchBatchSize = 50;
+    private const int ExistingMessageFlagFetchBatchSize = 250;
 
     private readonly ILogger _logger = Log.ForContext<UnifiedImapSynchronizer>();
     private readonly IFolderService _folderService;
@@ -47,6 +49,9 @@ public class UnifiedImapSynchronizer
         MessageSummaryItems.References |
         MessageSummaryItems.ModSeq |
         MessageSummaryItems.BodyStructure;
+    private readonly MessageSummaryItems _existingMailSynchronizationFlags =
+        MessageSummaryItems.Flags |
+        MessageSummaryItems.UniqueId;
 
     public UnifiedImapSynchronizer(
         IFolderService folderService,
@@ -182,15 +187,35 @@ public class UnifiedImapSynchronizer
 
         var downloadedMessageIds = new List<string>();
 
-        foreach (var batch in uids.Distinct().OrderBy(a => a.Id).Batch(50))
+        foreach (var batch in uids.Distinct().OrderBy(a => a.Id).Batch(ExistingMessageFlagFetchBatchSize))
         {
             cancellationToken.ThrowIfCancellationRequested();
 
-            var summaryBatch = await remoteFolder
-                .FetchAsync(new UniqueIdSet(batch.ToList(), SortOrder.Ascending), _mailSynchronizationFlags, cancellationToken)
-                .ConfigureAwait(false);
+            var batchUids = batch.ToList();
+            var existingMails = await _mailService.GetExistingMailsAsync(localFolder.Id, batchUids).ConfigureAwait(false);
+            var existingByUid = CreateExistingMailLookup(existingMails);
+            var existingUids = batchUids.Where(uid => existingByUid.ContainsKey(uid.Id)).ToList();
+            var newUids = batchUids.Where(uid => !existingByUid.ContainsKey(uid.Id)).ToList();
 
-            downloadedMessageIds.AddRange(await ProcessSummariesAsync(synchronizer, localFolder, summaryBatch, cancellationToken).ConfigureAwait(false));
+            if (existingUids.Count > 0)
+            {
+                var existingSummaryBatch = await remoteFolder
+                    .FetchAsync(new UniqueIdSet(existingUids, SortOrder.Ascending), _existingMailSynchronizationFlags, cancellationToken)
+                    .ConfigureAwait(false);
+
+                await ApplySummaryFlagUpdatesAsync(existingByUid, existingSummaryBatch).ConfigureAwait(false);
+            }
+
+            foreach (var newBatch in newUids.Batch(NewMessageFetchBatchSize))
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+
+                var newSummaryBatch = await remoteFolder
+                    .FetchAsync(new UniqueIdSet(newBatch.ToList(), SortOrder.Ascending), _mailSynchronizationFlags, cancellationToken)
+                    .ConfigureAwait(false);
+
+                downloadedMessageIds.AddRange(await ProcessSummariesCoreAsync(synchronizer, localFolder, newSummaryBatch, existingByUid, cancellationToken).ConfigureAwait(false));
+            }
         }
 
         UpdateHighestKnownUid(localFolder, remoteFolder, uids.Select(a => a.Id));
@@ -268,7 +293,29 @@ public class UnifiedImapSynchronizer
                     .ConfigureAwait(false);
             }
 
-            downloadedMessageIds = await DownloadMessagesByUidsAsync(client, remoteFolder, folder, changedUids, synchronizer, cancellationToken).ConfigureAwait(false);
+            var existingMails = await _mailService.GetExistingMailsAsync(folder.Id, changedUids).ConfigureAwait(false);
+            var existingByUid = CreateExistingMailLookup(existingMails);
+            var newOrUnknownUids = changedUids.Where(uid => !existingByUid.ContainsKey(uid.Id)).ToList();
+            var existingUidsWithoutFlagEvents = changedUids
+                .Where(uid => existingByUid.ContainsKey(uid.Id) && !changedFlags.ContainsKey(uid.Id))
+                .ToList();
+
+            if (existingUidsWithoutFlagEvents.Count > 0)
+            {
+                var missingEventSummaries = await remoteFolder
+                    .FetchAsync(new UniqueIdSet(existingUidsWithoutFlagEvents, SortOrder.Ascending), _existingMailSynchronizationFlags, cancellationToken)
+                    .ConfigureAwait(false);
+
+                foreach (var summary in missingEventSummaries)
+                {
+                    if (summary.UniqueId != UniqueId.Invalid && summary.Flags != null)
+                    {
+                        changedFlags[summary.UniqueId.Id] = summary.Flags.Value;
+                    }
+                }
+            }
+
+            downloadedMessageIds = await DownloadMessagesByUidsAsync(client, remoteFolder, folder, newOrUnknownUids, synchronizer, cancellationToken).ConfigureAwait(false);
 
             folder.HighestModeSeq = unchecked((long)remoteFolder.HighestModSeq);
 
@@ -456,11 +503,19 @@ public class UnifiedImapSynchronizer
         folder.UidValidity = remoteFolder.UidValidity;
     }
 
-    private async Task<List<string>> ProcessSummariesAsync(
+    private Task<List<string>> ProcessSummariesAsync(
         IImapSynchronizer synchronizer,
         MailItemFolder localFolder,
         IList<IMessageSummary> summaries,
         CancellationToken cancellationToken)
+        => ProcessSummariesCoreAsync(synchronizer, localFolder, summaries, existingByUid: null, cancellationToken);
+
+    private async Task<List<string>> ProcessSummariesCoreAsync(
+        IImapSynchronizer synchronizer,
+        MailItemFolder localFolder,
+        IList<IMessageSummary> summaries,
+        IReadOnlyDictionary<uint, MailCopy> existingByUid,
+        CancellationToken cancellationToken)
     {
         var downloadedMessageIds = new List<string>();
 
@@ -475,10 +530,8 @@ public class UnifiedImapSynchronizer
         if (uniqueIds.Count == 0)
             return downloadedMessageIds;
 
-        var existingMails = await _mailService.GetExistingMailsAsync(localFolder.Id, uniqueIds).ConfigureAwait(false);
-        var existingByUid = existingMails
-            .Select(m => (Uid: MailkitClientExtensions.ResolveUidStruct(m.Id), Mail: m))
-            .ToDictionary(a => a.Uid.Id, a => a.Mail);
+        existingByUid ??= CreateExistingMailLookup(await _mailService.GetExistingMailsAsync(localFolder.Id, uniqueIds).ConfigureAwait(false));
+        var pendingStateUpdates = new List<MailCopyStateUpdate>();
 
         foreach (var summary in summaries)
         {
@@ -491,7 +544,11 @@ public class UnifiedImapSynchronizer
             {
                 if (summary.Flags != null)
                 {
-                    await UpdateMailFlagsAsync(existingMail, summary.Flags.Value).ConfigureAwait(false);
+                    var pendingStateUpdate = CreateMailStateUpdate(existingMail, summary.Flags.Value);
+                    if (pendingStateUpdate != null)
+                    {
+                        pendingStateUpdates.Add(pendingStateUpdate);
+                    }
                 }
 
                 continue;
@@ -516,23 +573,79 @@ public class UnifiedImapSynchronizer
             }
         }
 
+        if (pendingStateUpdates.Count > 0)
+        {
+            await _mailService.ApplyMailStateUpdatesAsync(pendingStateUpdates).ConfigureAwait(false);
+        }
+
         return downloadedMessageIds;
     }
 
-    private async Task UpdateMailFlagsAsync(MailCopy mailCopy, MessageFlags flags)
+    private async Task ApplySummaryFlagUpdatesAsync(
+        IReadOnlyDictionary<uint, MailCopy> existingByUid,
+        IList<IMessageSummary> summaries)
+    {
+        if (existingByUid == null || existingByUid.Count == 0 || summaries == null || summaries.Count == 0)
+            return;
+
+        var pendingStateUpdates = new List<MailCopyStateUpdate>();
+
+        foreach (var summary in summaries)
+        {
+            if (summary.UniqueId == UniqueId.Invalid || summary.Flags == null)
+                continue;
+
+            if (!existingByUid.TryGetValue(summary.UniqueId.Id, out var existingMail))
+                continue;
+
+            var pendingStateUpdate = CreateMailStateUpdate(existingMail, summary.Flags.Value);
+            if (pendingStateUpdate != null)
+            {
+                pendingStateUpdates.Add(pendingStateUpdate);
+            }
+        }
+
+        if (pendingStateUpdates.Count > 0)
+        {
+            await _mailService.ApplyMailStateUpdatesAsync(pendingStateUpdates).ConfigureAwait(false);
+        }
+    }
+
+    private static IReadOnlyDictionary<uint, MailCopy> CreateExistingMailLookup(IEnumerable<MailCopy> existingMails)
+    {
+        var lookup = new Dictionary<uint, MailCopy>();
+
+        foreach (var mail in existingMails ?? [])
+        {
+            if (mail == null || string.IsNullOrEmpty(mail.Id))
+                continue;
+
+            try
+            {
+                lookup[MailkitClientExtensions.ResolveUidStruct(mail.Id).Id] = mail;
+            }
+            catch (ArgumentOutOfRangeException)
+            {
+            }
+        }
+
+        return lookup;
+    }
+
+    private static MailCopyStateUpdate CreateMailStateUpdate(MailCopy mailCopy, MessageFlags flags)
     {
         var isFlagged = MailkitClientExtensions.GetIsFlagged(flags);
         var isRead = MailkitClientExtensions.GetIsRead(flags);
 
-        if (isFlagged != mailCopy.IsFlagged)
-        {
-            await _mailService.ChangeFlagStatusAsync(mailCopy.Id, isFlagged).ConfigureAwait(false);
-        }
+        bool shouldUpdateFlagged = isFlagged != mailCopy.IsFlagged;
+        bool shouldUpdateRead = isRead != mailCopy.IsRead;
 
-        if (isRead != mailCopy.IsRead)
-        {
-            await _mailService.ChangeReadStatusAsync(mailCopy.Id, isRead).ConfigureAwait(false);
-        }
+        return !shouldUpdateFlagged && !shouldUpdateRead
+            ? null
+            : new MailCopyStateUpdate(
+                mailCopy.Id,
+                shouldUpdateRead ? isRead : null,
+                shouldUpdateFlagged ? isFlagged : null);
     }
 
     private async Task ApplyDeletedUidsAsync(MailItemFolder folder, IList<UniqueId> uniqueIds)
@@ -552,15 +665,14 @@ public class UnifiedImapSynchronizer
         if (changedFlags == null || changedFlags.Count == 0)
             return;
 
-        foreach (var changed in changedFlags)
-        {
-            var localMailCopyId = MailkitClientExtensions.CreateUid(folder.Id, changed.Key);
-            var isFlagged = MailkitClientExtensions.GetIsFlagged(changed.Value);
-            var isRead = MailkitClientExtensions.GetIsRead(changed.Value);
+        var stateUpdates = changedFlags
+            .Select(changed => new MailCopyStateUpdate(
+                MailkitClientExtensions.CreateUid(folder.Id, changed.Key),
+                MailkitClientExtensions.GetIsRead(changed.Value),
+                MailkitClientExtensions.GetIsFlagged(changed.Value)))
+            .ToList();
 
-            await _mailService.ChangeReadStatusAsync(localMailCopyId, isRead).ConfigureAwait(false);
-            await _mailService.ChangeFlagStatusAsync(localMailCopyId, isFlagged).ConfigureAwait(false);
-        }
+        await _mailService.ApplyMailStateUpdatesAsync(stateUpdates).ConfigureAwait(false);
     }
 
     private async Task ReconcileUidBasedFlagChangesAsync(MailItemFolder localFolder, IMailFolder remoteFolder, CancellationToken cancellationToken)
@@ -613,13 +725,14 @@ public class UnifiedImapSynchronizer
 
         var existingMarkReadCandidates = await FilterExistingRemoteUidsAsync(remoteFolder, markReadCandidates, cancellationToken).ConfigureAwait(false);
         var existingUnflagCandidates = await FilterExistingRemoteUidsAsync(remoteFolder, unflagCandidates, cancellationToken).ConfigureAwait(false);
+        var pendingStateUpdates = new List<MailCopyStateUpdate>();
 
         foreach (var uid in existingMarkReadCandidates)
         {
             if (!localByUid.TryGetValue(uid, out var localMail) || localMail.IsRead)
                 continue;
 
-            await _mailService.ChangeReadStatusAsync(localMail.Id, true).ConfigureAwait(false);
+            pendingStateUpdates.Add(new MailCopyStateUpdate(localMail.Id, IsRead: true));
         }
 
         foreach (var uid in remoteUnreadUids)
@@ -627,7 +740,7 @@ public class UnifiedImapSynchronizer
             if (!localByUid.TryGetValue(uid, out var localMail) || !localMail.IsRead)
                 continue;
 
-            await _mailService.ChangeReadStatusAsync(localMail.Id, false).ConfigureAwait(false);
+            pendingStateUpdates.Add(new MailCopyStateUpdate(localMail.Id, IsRead: false));
         }
 
         foreach (var uid in existingUnflagCandidates)
@@ -635,7 +748,7 @@ public class UnifiedImapSynchronizer
             if (!localByUid.TryGetValue(uid, out var localMail) || !localMail.IsFlagged)
                 continue;
 
-            await _mailService.ChangeFlagStatusAsync(localMail.Id, false).ConfigureAwait(false);
+            pendingStateUpdates.Add(new MailCopyStateUpdate(localMail.Id, IsFlagged: false));
         }
 
         foreach (var uid in remoteFlaggedUids)
@@ -643,7 +756,12 @@ public class UnifiedImapSynchronizer
             if (!localByUid.TryGetValue(uid, out var localMail) || localMail.IsFlagged)
                 continue;
 
-            await _mailService.ChangeFlagStatusAsync(localMail.Id, true).ConfigureAwait(false);
+            pendingStateUpdates.Add(new MailCopyStateUpdate(localMail.Id, IsFlagged: true));
+        }
+
+        if (pendingStateUpdates.Count > 0)
+        {
+            await _mailService.ApplyMailStateUpdatesAsync(pendingStateUpdates).ConfigureAwait(false);
         }
     }
 

Wino.Core/Synchronizers/ImapSynchronizer.cs

@@ -112,56 +112,104 @@ public class ImapSynchronizer : WinoSynchronizer<ImapRequest, ImapMessageCreatio
 
     public override List<IRequestBundle<ImapRequest>> Move(BatchMoveRequest requests)
     {
-        return CreateTaskBundle(async (client, item) =>
-        {
-            var sourceFolder = await client.GetFolderAsync(item.FromFolder.RemoteFolderId);
-            var destinationFolder = await client.GetFolderAsync(item.ToFolder.RemoteFolderId);
+        if (requests == null || requests.Count == 0)
+            return [];
+
+        return CreateSingleTaskBundle(async (client, _) =>
+        {
+            var sourceFolder = await client.GetFolderAsync(requests[0].FromFolder.RemoteFolderId).ConfigureAwait(false);
+            var destinationFolder = await client.GetFolderAsync(requests[0].ToFolder.RemoteFolderId).ConfigureAwait(false);
+            var uniqueIds = requests.Select(item => GetUniqueId(item.Item.Id)).ToList();
 
-            // Only opening source folder is enough.
             await sourceFolder.OpenAsync(FolderAccess.ReadWrite).ConfigureAwait(false);
-            await sourceFolder.MoveToAsync(GetUniqueId(item.Item.Id), destinationFolder).ConfigureAwait(false);
-            await sourceFolder.CloseAsync().ConfigureAwait(false);
-        }, requests);
+            try
+            {
+                await sourceFolder.MoveToAsync(uniqueIds, destinationFolder).ConfigureAwait(false);
+            }
+            finally
+            {
+                await sourceFolder.CloseAsync().ConfigureAwait(false);
+            }
+        }, requests[0], requests);
     }
 
     public override List<IRequestBundle<ImapRequest>> ChangeFlag(BatchChangeFlagRequest requests)
     {
-        return CreateTaskBundle(async (client, item) =>
+        if (requests == null || requests.Count == 0)
+            return [];
+
+        return CreateSingleTaskBundle(async (client, _) =>
         {
-            var folder = item.Item.AssignedFolder;
-            var remoteFolder = await client.GetFolderAsync(folder.RemoteFolderId);
+            var folder = requests[0].Item.AssignedFolder;
+            var remoteFolder = await client.GetFolderAsync(folder.RemoteFolderId).ConfigureAwait(false);
+            var uniqueIds = requests.Select(item => GetUniqueId(item.Item.Id)).ToList();
+            var request = new StoreFlagsRequest(requests[0].IsFlagged ? StoreAction.Add : StoreAction.Remove, MessageFlags.Flagged)
+            {
+                Silent = true
+            };
 
             await remoteFolder.OpenAsync(FolderAccess.ReadWrite).ConfigureAwait(false);
-            await remoteFolder.StoreAsync(GetUniqueId(item.Item.Id), new StoreFlagsRequest(item.IsFlagged ? StoreAction.Add : StoreAction.Remove, MessageFlags.Flagged) { Silent = true }).ConfigureAwait(false);
-            await remoteFolder.CloseAsync().ConfigureAwait(false);
-        }, requests);
+            try
+            {
+                await remoteFolder.StoreAsync(uniqueIds, request).ConfigureAwait(false);
+            }
+            finally
+            {
+                await remoteFolder.CloseAsync().ConfigureAwait(false);
+            }
+        }, requests[0], requests);
     }
 
     public override List<IRequestBundle<ImapRequest>> Delete(BatchDeleteRequest requests)
     {
-        return CreateTaskBundle(async (client, request) =>
+        if (requests == null || requests.Count == 0)
+            return [];
+
+        return CreateSingleTaskBundle(async (client, _) =>
         {
-            var folder = request.Item.AssignedFolder;
+            var folder = requests[0].Item.AssignedFolder;
             var remoteFolder = await client.GetFolderAsync(folder.RemoteFolderId).ConfigureAwait(false);
+            var uniqueIds = requests.Select(request => GetUniqueId(request.Item.Id)).ToList();
+            var storeRequest = new StoreFlagsRequest(StoreAction.Add, MessageFlags.Deleted) { Silent = true };
 
             await remoteFolder.OpenAsync(FolderAccess.ReadWrite).ConfigureAwait(false);
-            await remoteFolder.AddFlagsAsync(GetUniqueId(request.Item.Id), MessageFlags.Deleted, true);
-            await remoteFolder.ExpungeAsync().ConfigureAwait(false);
-            await remoteFolder.CloseAsync().ConfigureAwait(false);
-        }, requests);
+            try
+            {
+                await remoteFolder.StoreAsync(uniqueIds, storeRequest).ConfigureAwait(false);
+                await remoteFolder.ExpungeAsync(uniqueIds).ConfigureAwait(false);
+            }
+            finally
+            {
+                await remoteFolder.CloseAsync().ConfigureAwait(false);
+            }
+        }, requests[0], requests);
     }
 
     public override List<IRequestBundle<ImapRequest>> MarkRead(BatchMarkReadRequest requests)
     {
-        return CreateTaskBundle(async (client, request) =>
+        if (requests == null || requests.Count == 0)
+            return [];
+
+        return CreateSingleTaskBundle(async (client, _) =>
         {
-            var folder = request.Item.AssignedFolder;
-            var remoteFolder = await client.GetFolderAsync(folder.RemoteFolderId);
+            var folder = requests[0].Item.AssignedFolder;
+            var remoteFolder = await client.GetFolderAsync(folder.RemoteFolderId).ConfigureAwait(false);
+            var uniqueIds = requests.Select(request => GetUniqueId(request.Item.Id)).ToList();
+            var storeRequest = new StoreFlagsRequest(requests[0].IsRead ? StoreAction.Add : StoreAction.Remove, MessageFlags.Seen)
+            {
+                Silent = true
+            };
 
             await remoteFolder.OpenAsync(FolderAccess.ReadWrite).ConfigureAwait(false);
-            await remoteFolder.StoreAsync(GetUniqueId(request.Item.Id), new StoreFlagsRequest(request.IsRead ? StoreAction.Add : StoreAction.Remove, MessageFlags.Seen) { Silent = true }).ConfigureAwait(false);
-            await remoteFolder.CloseAsync().ConfigureAwait(false);
-        }, requests);
+            try
+            {
+                await remoteFolder.StoreAsync(uniqueIds, storeRequest).ConfigureAwait(false);
+            }
+            finally
+            {
+                await remoteFolder.CloseAsync().ConfigureAwait(false);
+            }
+        }, requests[0], requests);
     }
 
     public override List<IRequestBundle<ImapRequest>> CreateDraft(CreateDraftRequest request)
@@ -718,13 +766,7 @@ public class ImapSynchronizer : WinoSynchronizer<ImapRequest, ImapMessageCreatio
         // First apply the UI changes for each bundle.
         // This is important to reflect changes to the UI before the network call is done.
 
-        foreach (var item in batchedRequests)
-        {
-            if (ShouldApplyOptimisticUIChanges(item.Request))
-            {
-                item.Request.ApplyUIChanges();
-            }
-        }
+        ApplyOptimisticUiChanges(batchedRequests, ShouldApplyOptimisticUIChanges);
 
         // All task bundles will execute on the same client.
         // Tasks themselves don't pull the client from the pool
@@ -754,7 +796,7 @@ public class ImapSynchronizer : WinoSynchronizer<ImapRequest, ImapMessageCreatio
 
                 if (ShouldApplyOptimisticUIChanges(item.Request))
                 {
-                    item.Request.RevertUIChanges();
+                    item.UIChangeRequest?.RevertUIChanges();
                 }
 
                 isCrashed = true;
@@ -795,7 +837,7 @@ public class ImapSynchronizer : WinoSynchronizer<ImapRequest, ImapMessageCreatio
 
                     if (ShouldApplyOptimisticUIChanges(item.Request))
                     {
-                        item.Request.RevertUIChanges();
+                        item.UIChangeRequest?.RevertUIChanges();
                     }
                     throw;
                 }

Wino.Core/Synchronizers/OutlookSynchronizer.cs

@@ -2020,10 +2020,7 @@ public class OutlookSynchronizer : WinoSynchronizer<RequestInformation, Message,
     {
         // First apply all UI changes immediately before any batching.
         // This ensures UI reflects changes right away, regardless of batch processing.
-        foreach (var bundle in batchedRequests)
-        {
-            bundle.UIChangeRequest?.ApplyUIChanges();
-        }
+        ApplyOptimisticUiChanges(batchedRequests);
 
         // SendDraft requests may include large attachments, which require upload sessions.
         // Upload these attachments before the batched patch/send sequence.

Wino.Core/Synchronizers/WinoSynchronizer.cs

@@ -161,11 +161,11 @@ public abstract class WinoSynchronizer<TBaseRequest, TMessageType, TCalendarEven
 
                 foreach (var group in keys)
                 {
-                    var key = group.Key;
+                    var firstRequest = group.FirstOrDefault();
 
-                    if (key is MailSynchronizerOperation mailSynchronizerOperation)
+                    if (firstRequest is IMailActionRequest mailActionRequest)
                     {
-                        switch (mailSynchronizerOperation)
+                        switch (mailActionRequest.Operation)
                         {
                             case MailSynchronizerOperation.MarkRead:
                                 nativeRequests.AddRange(MarkRead(new BatchMarkReadRequest(group.Cast<MarkReadRequest>())));
@@ -204,9 +204,9 @@ public abstract class WinoSynchronizer<TBaseRequest, TMessageType, TCalendarEven
                                 break;
                         }
                     }
-                    else if (key is FolderSynchronizerOperation folderSynchronizerOperation)
+                    else if (firstRequest is IFolderActionRequest folderActionRequest)
                     {
-                        switch (folderSynchronizerOperation)
+                        switch (folderActionRequest.Operation)
                         {
                             case FolderSynchronizerOperation.RenameFolder:
                                 nativeRequests.AddRange(RenameFolder(group.ElementAt(0) as RenameFolderRequest));
@@ -230,9 +230,9 @@ public abstract class WinoSynchronizer<TBaseRequest, TMessageType, TCalendarEven
                                 break;
                         }
                     }
-                    else if (key is CategorySynchronizerOperation categorySynchronizerOperation)
+                    else if (firstRequest is ICategoryActionRequest categoryActionRequest)
                     {
-                        switch (categorySynchronizerOperation)
+                        switch (categoryActionRequest.Operation)
                         {
                             case CategorySynchronizerOperation.CreateCategory:
                                 nativeRequests.AddRange(CreateCategory(group.ElementAt(0) as MailCategoryCreateRequest));

Wino.Mail.ViewModels/Collections/WinoMailCollection.cs

@@ -14,6 +14,7 @@ using Wino.Core.Domain.Enums;
 using Wino.Core.Domain.Interfaces;
 using Wino.Mail.ViewModels.Data;
 using Wino.Messaging.Client.Mails;
+using Wino.Messaging.UI;
 
 namespace Wino.Mail.ViewModels.Collections;
 
@@ -895,6 +896,121 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
             return UpdateExistingItemAsync(itemContainer, updatedMailCopy, mailUpdateSource, changedProperties);
         });
 
+    public Task UpdateMailStateAsync(MailStateChange updatedState, EntityUpdateSource mailUpdateSource)
+        => RunSerializedAsync(() =>
+        {
+            if (updatedState == null)
+                return Task.CompletedTask;
+
+            var itemContainer = GetMailItemContainer(updatedState.UniqueId);
+
+            if (itemContainer?.ItemViewModel == null)
+            {
+                return Task.CompletedTask;
+            }
+
+            return UpdateExistingMailStateAsync(itemContainer, updatedState, mailUpdateSource);
+        });
+
+    public Task UpdateMailStatesAsync(IEnumerable<MailStateChange> updatedStates, EntityUpdateSource mailUpdateSource)
+        => RunSerializedAsync(() => UpdateMailStatesInternalAsync(updatedStates, mailUpdateSource));
+
+    public Task UpdateMailCopiesAsync(IEnumerable<MailCopy> updatedMailCopies, EntityUpdateSource mailUpdateSource, MailCopyChangeFlags changedProperties = MailCopyChangeFlags.None)
+        => RunSerializedAsync(() => UpdateMailCopiesInternalAsync(updatedMailCopies, mailUpdateSource, changedProperties));
+
+    private async Task UpdateExistingMailStateAsync(MailItemContainer itemContainer, MailStateChange updatedState, EntityUpdateSource mailUpdateSource)
+    {
+        if (itemContainer?.ItemViewModel == null || updatedState == null)
+            return;
+
+        var existingItem = itemContainer.ItemViewModel;
+
+        await ExecuteUIThread(() =>
+        {
+            var appliedChanges = existingItem.ApplyStateChanges(updatedState.IsRead, updatedState.IsFlagged);
+            existingItem.IsBusy = mailUpdateSource == EntityUpdateSource.ClientUpdated;
+
+            if (itemContainer.ThreadViewModel != null && appliedChanges != MailCopyChangeFlags.None)
+            {
+                itemContainer.ThreadViewModel.NotifyMailItemUpdated(existingItem, appliedChanges);
+            }
+        });
+    }
+
+    private async Task UpdateMailStatesInternalAsync(IEnumerable<MailStateChange> updatedStates, EntityUpdateSource mailUpdateSource)
+    {
+        var updates = updatedStates?
+            .Where(x => x != null)
+            .GroupBy(x => x.UniqueId)
+            .Select(group =>
+            {
+                var updatedState = group.Last();
+                return new
+                {
+                    UpdatedState = updatedState,
+                    ItemContainer = GetMailItemContainer(updatedState.UniqueId)
+                };
+            })
+            .Where(x => x.ItemContainer?.ItemViewModel != null)
+            .ToList() ?? [];
+
+        if (updates.Count == 0)
+            return;
+
+        await ExecuteUIThread(() =>
+        {
+            foreach (var update in updates)
+            {
+                var existingItem = update.ItemContainer.ItemViewModel;
+                var appliedChanges = existingItem.ApplyStateChanges(update.UpdatedState.IsRead, update.UpdatedState.IsFlagged);
+                existingItem.IsBusy = mailUpdateSource == EntityUpdateSource.ClientUpdated;
+
+                if (update.ItemContainer.ThreadViewModel != null && appliedChanges != MailCopyChangeFlags.None)
+                {
+                    update.ItemContainer.ThreadViewModel.NotifyMailItemUpdated(existingItem, appliedChanges);
+                }
+            }
+        });
+    }
+
+    private async Task UpdateMailCopiesInternalAsync(IEnumerable<MailCopy> updatedMailCopies, EntityUpdateSource mailUpdateSource, MailCopyChangeFlags changedProperties)
+    {
+        var updates = updatedMailCopies?
+            .Where(x => x != null)
+            .GroupBy(x => x.UniqueId)
+            .Select(group =>
+            {
+                var updatedMail = group.First();
+                return new
+                {
+                    UpdatedMail = updatedMail,
+                    ItemContainer = GetMailItemContainer(updatedMail.UniqueId)
+                };
+            })
+            .Where(x => x.ItemContainer?.ItemViewModel != null)
+            .ToList() ?? [];
+
+        if (updates.Count == 0)
+            return;
+
+        await ExecuteUIThread(() =>
+        {
+            foreach (var update in updates)
+            {
+                var updatedMail = update.UpdatedMail;
+                var itemContainer = update.ItemContainer;
+                var existingItem = itemContainer.ItemViewModel;
+                var appliedChanges = existingItem.UpdateFrom(updatedMail, changedProperties);
+                existingItem.IsBusy = mailUpdateSource == EntityUpdateSource.ClientUpdated;
+
+                if (itemContainer.ThreadViewModel != null && appliedChanges != MailCopyChangeFlags.None)
+                {
+                    itemContainer.ThreadViewModel.NotifyMailItemUpdated(existingItem, appliedChanges);
+                }
+            }
+        });
+    }
+
     public MailItemViewModel GetFirst() => AllItems.ElementAtOrDefault(0);
 
     public MailItemViewModel GetNextItem(MailCopy mailCopy)
@@ -963,7 +1079,32 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
     public Task RemoveAsync(MailCopy removeItem)
         => RunSerializedAsync(() => RemoveInternalAsync(removeItem));
 
+    public Task RemoveRangeAsync(IEnumerable<MailCopy> removeItems)
+        => RunSerializedAsync(() => RemoveRangeInternalAsync(removeItems));
+
     private async Task RemoveInternalAsync(MailCopy removeItem)
+        => await RemoveInternalAsync(removeItem, notifySelectionChanges: true);
+
+    private async Task RemoveRangeInternalAsync(IEnumerable<MailCopy> removeItems)
+    {
+        var distinctItems = removeItems?
+            .Where(x => x != null)
+            .GroupBy(x => x.UniqueId)
+            .Select(group => group.First())
+            .ToList() ?? [];
+
+        if (distinctItems.Count == 0)
+            return;
+
+        foreach (var removeItem in distinctItems)
+        {
+            await RemoveInternalAsync(removeItem, notifySelectionChanges: false);
+        }
+
+        await NotifySelectionChangesAsync();
+    }
+
+    private async Task RemoveInternalAsync(MailCopy removeItem, bool notifySelectionChanges)
     {
         var itemContainer = GetMailItemContainer(removeItem.UniqueId);
 
@@ -1030,7 +1171,10 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
             }
         }
 
-        await NotifySelectionChangesAsync();
+        if (notifySelectionChanges)
+        {
+            await NotifySelectionChangesAsync();
+        }
     }
 
     private IEnumerable<IMailListItem> AllItemsIncludingThreads
@@ -1207,4 +1351,5 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
             ItemSelectionChanged?.Invoke(this, null);
         });
     }
+
 }

Wino.Mail.ViewModels/Data/MailItemViewModel.cs

@@ -320,6 +320,30 @@ public partial class MailItemViewModel(MailCopy mailCopy) : ObservableRecipient,
         return changedFlags;
     }
 
+    public MailCopyChangeFlags ApplyStateChanges(bool? isRead = null, bool? isFlagged = null)
+    {
+        var changedFlags = MailCopyChangeFlags.None;
+
+        if (isRead.HasValue && MailCopy.IsRead != isRead.Value)
+        {
+            MailCopy.IsRead = isRead.Value;
+            changedFlags |= MailCopyChangeFlags.IsRead;
+        }
+
+        if (isFlagged.HasValue && MailCopy.IsFlagged != isFlagged.Value)
+        {
+            MailCopy.IsFlagged = isFlagged.Value;
+            changedFlags |= MailCopyChangeFlags.IsFlagged;
+        }
+
+        if (changedFlags != MailCopyChangeFlags.None)
+        {
+            RaisePropertyChanges(changedFlags);
+        }
+
+        return changedFlags;
+    }
+
     private static MailCopyChangeFlags SetIfChanged<T>(T currentValue, T newValue, Action<T> setter, MailCopyChangeFlags flag)
     {
         if (EqualityComparer<T>.Default.Equals(currentValue, newValue))

Wino.Mail.ViewModels/MailBaseViewModel.cs

@@ -1,4 +1,5 @@
 using CommunityToolkit.Mvvm.Messaging;
+using System.Collections.Generic;
 using Wino.Core.Domain.Entities.Mail;
 using Wino.Core.Domain.Entities.Shared;
 using Wino.Core.Domain.Enums;
@@ -10,8 +11,13 @@ namespace Wino.Mail.ViewModels;
 
 public class MailBaseViewModel : CoreBaseViewModel,
     IRecipient<MailAddedMessage>,
+    IRecipient<BulkMailAddedMessage>,
     IRecipient<MailRemovedMessage>,
+    IRecipient<BulkMailRemovedMessage>,
+    IRecipient<MailStateUpdatedMessage>,
+    IRecipient<BulkMailStateUpdatedMessage>,
     IRecipient<MailUpdatedMessage>,
+    IRecipient<BulkMailUpdatedMessage>,
     IRecipient<MailDownloadedMessage>,
     IRecipient<DraftCreated>,
     IRecipient<DraftFailed>,
@@ -21,8 +27,41 @@ public class MailBaseViewModel : CoreBaseViewModel,
     IRecipient<FolderSynchronizationEnabled>
 {
     protected virtual void OnMailAdded(MailCopy addedMail, EntityUpdateSource source) { }
+    protected virtual void OnBulkMailAdded(IReadOnlyList<MailCopy> addedMails, EntityUpdateSource source)
+    {
+        foreach (var addedMail in addedMails ?? [])
+        {
+            OnMailAdded(addedMail, source);
+        }
+    }
+
     protected virtual void OnMailRemoved(MailCopy removedMail, EntityUpdateSource source) { }
+    protected virtual void OnBulkMailRemoved(IReadOnlyList<MailCopy> removedMails, EntityUpdateSource source)
+    {
+        foreach (var removedMail in removedMails ?? [])
+        {
+            OnMailRemoved(removedMail, source);
+        }
+    }
+
+    protected virtual void OnMailStateUpdated(MailStateChange updatedState, EntityUpdateSource source) { }
+    protected virtual void OnBulkMailStateUpdated(IReadOnlyList<MailStateChange> updatedStates, EntityUpdateSource source)
+    {
+        foreach (var updatedState in updatedStates ?? [])
+        {
+            OnMailStateUpdated(updatedState, source);
+        }
+    }
+
     protected virtual void OnMailUpdated(MailCopy updatedMail, EntityUpdateSource source, MailCopyChangeFlags changedProperties) { }
+    protected virtual void OnBulkMailUpdated(IReadOnlyList<MailCopy> updatedMails, EntityUpdateSource source, MailCopyChangeFlags changedProperties)
+    {
+        foreach (var updatedMail in updatedMails ?? [])
+        {
+            OnMailUpdated(updatedMail, source, changedProperties);
+        }
+    }
+
     protected virtual void OnMailDownloaded(MailCopy downloadedMail) { }
     protected virtual void OnDraftCreated(MailCopy draftMail, MailAccount account) { }
     protected virtual void OnDraftFailed(MailCopy draftMail, MailAccount account) { }
@@ -32,8 +71,13 @@ public class MailBaseViewModel : CoreBaseViewModel,
     protected virtual void OnFolderSynchronizationEnabled(IMailItemFolder mailItemFolder) { }
 
     void IRecipient<MailAddedMessage>.Receive(MailAddedMessage message) => OnMailAdded(message.AddedMail, message.Source);
+    void IRecipient<BulkMailAddedMessage>.Receive(BulkMailAddedMessage message) => OnBulkMailAdded(message.AddedMails, message.Source);
     void IRecipient<MailRemovedMessage>.Receive(MailRemovedMessage message) => OnMailRemoved(message.RemovedMail, message.Source);
+    void IRecipient<BulkMailRemovedMessage>.Receive(BulkMailRemovedMessage message) => OnBulkMailRemoved(message.RemovedMails, message.Source);
+    void IRecipient<MailStateUpdatedMessage>.Receive(MailStateUpdatedMessage message) => OnMailStateUpdated(message.UpdatedState, message.Source);
+    void IRecipient<BulkMailStateUpdatedMessage>.Receive(BulkMailStateUpdatedMessage message) => OnBulkMailStateUpdated(message.UpdatedStates, message.Source);
     void IRecipient<MailUpdatedMessage>.Receive(MailUpdatedMessage message) => OnMailUpdated(message.UpdatedMail, message.Source, message.ChangedProperties);
+    void IRecipient<BulkMailUpdatedMessage>.Receive(BulkMailUpdatedMessage message) => OnBulkMailUpdated(message.UpdatedMails, message.Source, message.ChangedProperties);
     void IRecipient<MailDownloadedMessage>.Receive(MailDownloadedMessage message) => OnMailDownloaded(message.DownloadedMail);
 
     void IRecipient<DraftMapped>.Receive(DraftMapped message) => OnDraftMapped(message.LocalDraftCopyId, message.RemoteDraftCopyId);
@@ -51,8 +95,13 @@ public class MailBaseViewModel : CoreBaseViewModel,
         UnregisterRecipients();
 
         Messenger.Register<MailAddedMessage>(this);
+        Messenger.Register<BulkMailAddedMessage>(this);
         Messenger.Register<MailRemovedMessage>(this);
+        Messenger.Register<BulkMailRemovedMessage>(this);
+        Messenger.Register<MailStateUpdatedMessage>(this);
+        Messenger.Register<BulkMailStateUpdatedMessage>(this);
         Messenger.Register<MailUpdatedMessage>(this);
+        Messenger.Register<BulkMailUpdatedMessage>(this);
         Messenger.Register<MailDownloadedMessage>(this);
         Messenger.Register<DraftCreated>(this);
         Messenger.Register<DraftFailed>(this);
@@ -67,8 +116,13 @@ public class MailBaseViewModel : CoreBaseViewModel,
         base.UnregisterRecipients();
 
         Messenger.Unregister<MailAddedMessage>(this);
+        Messenger.Unregister<BulkMailAddedMessage>(this);
         Messenger.Unregister<MailRemovedMessage>(this);
+        Messenger.Unregister<BulkMailRemovedMessage>(this);
+        Messenger.Unregister<MailStateUpdatedMessage>(this);
+        Messenger.Unregister<BulkMailStateUpdatedMessage>(this);
         Messenger.Unregister<MailUpdatedMessage>(this);
+        Messenger.Unregister<BulkMailUpdatedMessage>(this);
         Messenger.Unregister<MailDownloadedMessage>(this);
         Messenger.Unregister<DraftCreated>(this);
         Messenger.Unregister<DraftFailed>(this);

Wino.Mail.ViewModels/MailListPageViewModel.cs

@@ -23,6 +23,7 @@ using Wino.Core.Domain.Models.MailItem;
 using Wino.Core.Domain.Models.Menus;
 using Wino.Core.Domain.Models.Navigation;
 using Wino.Core.Domain.Models.Reader;
+using Wino.Core.Domain.Models.Synchronization;
 using Wino.Core.Requests.Mail;
 using Wino.Core.Services;
 using Wino.Mail.ViewModels.Collections;
@@ -77,6 +78,7 @@ public partial class MailListPageViewModel : MailBaseViewModel,
     private readonly INotificationBuilder _notificationBuilder;
     private readonly IFolderService _folderService;
     private readonly IContextMenuItemService _contextMenuItemService;
+    private readonly ILogger _logger = Log.ForContext<MailListPageViewModel>();
     private readonly IMailCategoryService _mailCategoryService;
     private readonly IWinoRequestDelegator _winoRequestDelegator;
     private readonly IKeyPressService _keyPressService;
@@ -492,29 +494,29 @@ public partial class MailListPageViewModel : MailBaseViewModel,
     {
         if (!CanSynchronize) return;
 
-        _notificationBuilder.CreateNotificationsAsync(MailCollection.SelectedItems.Select(a => a.MailCopy));
-        return;
+        //_notificationBuilder.CreateNotificationsAsync(MailCollection.SelectedItems.Select(a => a.MailCopy));
+        //return;
 
         // Only synchronize listed folders.
 
         // When doing linked inbox sync, we need to save the sync id to report progress back only once.
         // Otherwise, we will report progress for each folder and that's what we don't want.
 
-        //trackingSynchronizationId = Guid.NewGuid();
-        //completedTrackingSynchronizationCount = 0;
+        trackingSynchronizationId = Guid.NewGuid();
+        completedTrackingSynchronizationCount = 0;
 
-        //foreach (var folder in ActiveFolder.HandlingFolders)
-        //{
-        //    var options = new MailSynchronizationOptions()
-        //    {
-        //        AccountId = folder.MailAccountId,
-        //        Type = MailSynchronizationType.CustomFolders,
-        //        SynchronizationFolderIds = [folder.Id],
-        //        GroupedSynchronizationTrackingId = trackingSynchronizationId
-        //    };
+        foreach (var folder in ActiveFolder.HandlingFolders)
+        {
+            var options = new MailSynchronizationOptions()
+            {
+                AccountId = folder.MailAccountId,
+                Type = MailSynchronizationType.CustomFolders,
+                SynchronizationFolderIds = [folder.Id],
+                GroupedSynchronizationTrackingId = trackingSynchronizationId
+            };
 
-        //    Messenger.Send(new NewMailSynchronizationRequested(options));
-        //}
+            Messenger.Send(new NewMailSynchronizationRequested(options));
+        }
     }
 
     [RelayCommand]
@@ -749,7 +751,7 @@ public partial class MailListPageViewModel : MailBaseViewModel,
             return;
 
         var requests = new List<IRequestBase>();
-        foreach (var mailItem in targetList.Select(a => a.MailCopy).DistinctBy(a => a.UniqueId))
+        foreach (var mailItem in targetList.Select(a => a.MailCopy).GroupBy(a => a.UniqueId).Select(group => group.First()))
         {
             var categoryNames = await _mailCategoryService.GetCategoryNamesForMailAsync(mailItem.UniqueId).ConfigureAwait(false);
             requests.Add(new MailCategoryAssignmentRequest(mailItem, category.Id, category.Name, categoryNames, !isAssignedToAll));
@@ -958,7 +960,6 @@ public partial class MailListPageViewModel : MailBaseViewModel,
     protected override async void OnMailUpdated(MailCopy updatedMail, EntityUpdateSource source, MailCopyChangeFlags changedProperties)
     {
         base.OnMailUpdated(updatedMail, source, changedProperties);
-
         try
         {
             await listManipulationSemepahore.WaitAsync();
@@ -983,6 +984,115 @@ public partial class MailListPageViewModel : MailBaseViewModel,
         await ExecuteUIThread(() => { SetupTopBarActions(); });
     }
 
+    protected override async void OnMailStateUpdated(MailStateChange updatedState, EntityUpdateSource source)
+    {
+        base.OnMailStateUpdated(updatedState, source);
+
+        if (updatedState == null)
+            return;
+
+        try
+        {
+            await listManipulationSemepahore.WaitAsync();
+
+            if (!MailCollection.ContainsMailUniqueId(updatedState.UniqueId))
+                return;
+
+            await MailCollection.UpdateMailStateAsync(updatedState, source);
+        }
+        finally
+        {
+            listManipulationSemepahore.Release();
+        }
+
+        await ExecuteUIThread(() => { SetupTopBarActions(); });
+    }
+
+    protected override async void OnBulkMailStateUpdated(IReadOnlyList<MailStateChange> updatedStates, EntityUpdateSource source)
+    {
+        var targetStates = updatedStates?
+            .Where(x => x != null)
+            .GroupBy(x => x.UniqueId)
+            .Select(group => group.Last())
+            .ToList() ?? [];
+
+        if (targetStates.Count == 0)
+            return;
+
+        try
+        {
+            await listManipulationSemepahore.WaitAsync();
+
+            var listedStates = targetStates
+                .Where(state => MailCollection.ContainsMailUniqueId(state.UniqueId))
+                .ToList();
+
+            if (listedStates.Count == 0)
+                return;
+
+            await MailCollection.UpdateMailStatesAsync(listedStates, source);
+        }
+        finally
+        {
+            listManipulationSemepahore.Release();
+        }
+
+        await ExecuteUIThread(() => { SetupTopBarActions(); });
+    }
+
+    protected override async void OnBulkMailUpdated(IReadOnlyList<MailCopy> updatedMails, EntityUpdateSource source, MailCopyChangeFlags changedProperties)
+    {
+        var targetMails = updatedMails?
+            .Where(x => x != null)
+            .GroupBy(x => x.UniqueId)
+            .Select(group => group.First())
+            .ToList() ?? [];
+
+        if (targetMails.Count == 0)
+            return;
+
+        try
+        {
+            await listManipulationSemepahore.WaitAsync();
+
+            var listedMails = targetMails
+                .Where(mail => MailCollection.ContainsMailUniqueId(mail.UniqueId))
+                .ToList();
+
+            if (listedMails.Count == 0)
+                return;
+
+            var mailsToRemove = listedMails
+                .Where(ShouldRemoveUpdatedMailFromCurrentList)
+                .ToList();
+
+            var mailIdsToRemove = mailsToRemove.Select(x => x.UniqueId).ToHashSet();
+            var mailsToUpdate = listedMails
+                .Where(mail => !mailIdsToRemove.Contains(mail.UniqueId))
+                .ToList();
+
+            if (mailsToRemove.Count > 0)
+            {
+                await MailCollection.RemoveRangeAsync(mailsToRemove);
+            }
+
+            if (mailsToUpdate.Count > 0)
+            {
+                await MailCollection.UpdateMailCopiesAsync(mailsToUpdate, source, changedProperties);
+            }
+
+            await ExecuteUIThread(() =>
+            {
+                NotifyItemFoundState();
+                SetupTopBarActions();
+            });
+        }
+        finally
+        {
+            listManipulationSemepahore.Release();
+        }
+    }
+
     protected override async void OnMailRemoved(MailCopy removedMail, EntityUpdateSource source)
     {
         base.OnMailRemoved(removedMail, source);
@@ -1003,18 +1113,18 @@ public partial class MailListPageViewModel : MailBaseViewModel,
 
             if (removedItemExistsInCurrentList && !isDeletedByGmailUnreadFolderAction)
             {
-                bool isDeletedMailSelected = MailCollection.SelectedItems.Any(a => a.MailCopy.UniqueId == removedMail.UniqueId);
-
-                // Automatically select the next item in the list if the setting is enabled.
                 MailItemViewModel nextItem = null;
+                bool isDeletedMailSelected = false;
 
-                if (isDeletedMailSelected && PreferencesService.AutoSelectNextItem)
+                await ExecuteUIThread(() =>
                 {
-                    await ExecuteUIThread(() =>
+                    isDeletedMailSelected = MailCollection.SelectedItems.Any(a => a.MailCopy.UniqueId == removedMail.UniqueId);
+
+                    if (isDeletedMailSelected && PreferencesService.AutoSelectNextItem)
                     {
                         nextItem = MailCollection.GetNextItem(removedMail);
-                    });
-                }
+                    }
+                });
 
                 // RemoveAsync already handles UI threading internally
                 await MailCollection.RemoveAsync(removedMail);
@@ -1044,6 +1154,115 @@ public partial class MailListPageViewModel : MailBaseViewModel,
         }
     }
 
+    protected override async void OnBulkMailRemoved(IReadOnlyList<MailCopy> removedMails, EntityUpdateSource source)
+    {
+        var targetMails = removedMails?
+            .Where(x => x != null && x.AssignedAccount != null)
+            .GroupBy(x => x.UniqueId)
+            .Select(group => group.First())
+            .ToList() ?? [];
+
+        if (targetMails.Count == 0)
+            return;
+
+        try
+        {
+            await listManipulationSemepahore.WaitAsync();
+
+            var existingMails = targetMails
+                .Where(mail => MailCollection.ContainsMailUniqueId(mail.UniqueId))
+                .ToList();
+
+            if (existingMails.Count == 0)
+                return;
+
+            var removedMailIds = existingMails.Select(mail => mail.UniqueId).ToHashSet();
+            var shouldClearSelection = false;
+
+            await ExecuteUIThread(() =>
+            {
+                shouldClearSelection = MailCollection.SelectedItems.Any(item => removedMailIds.Contains(item.MailCopy.UniqueId));
+            });
+
+            await MailCollection.RemoveRangeAsync(existingMails);
+
+            if (shouldClearSelection)
+            {
+                await MailCollection.UnselectAllAsync();
+            }
+
+            await ExecuteUIThread(() =>
+            {
+                NotifyItemFoundState();
+                SetupTopBarActions();
+            });
+        }
+        finally
+        {
+            listManipulationSemepahore.Release();
+        }
+    }
+
+    protected override async void OnBulkMailAdded(IReadOnlyList<MailCopy> addedMails, EntityUpdateSource source)
+    {
+        var targetMails = addedMails?
+            .Where(x => x != null)
+            .GroupBy(x => x.UniqueId)
+            .Select(group => group.First())
+            .ToList() ?? [];
+
+        if (targetMails.Count == 0)
+            return;
+
+        try
+        {
+            await listManipulationSemepahore.WaitAsync();
+
+            var mailsToAdd = new List<MailCopy>();
+
+            foreach (var addedMail in targetMails)
+            {
+                if (MailCollection.ContainsMailUniqueId(addedMail.UniqueId))
+                    continue;
+
+                if (!ShouldIncludeAddedMailInCurrentList(addedMail))
+                    continue;
+
+                if (ShouldPreventItemAdd(addedMail))
+                    continue;
+
+                if (SelectedFolderPivot?.IsFocused is bool isFocused && addedMail.IsFocused != isFocused)
+                    continue;
+
+                if (IsInSearchMode)
+                {
+                    if (IsOnlineSearchEnabled || AreSearchResultsOnline)
+                        continue;
+
+                    if (!IsMailMatchingLocalSearch(addedMail))
+                        continue;
+                }
+
+                mailsToAdd.Add(addedMail);
+            }
+
+            if (mailsToAdd.Count == 0)
+                return;
+
+            await MailCollection.AddRangeAsync(mailsToAdd.Select(mail => new MailItemViewModel(mail)), false);
+
+            await ExecuteUIThread(() =>
+            {
+                NotifyItemFoundState();
+                SetupTopBarActions();
+            });
+        }
+        finally
+        {
+            listManipulationSemepahore.Release();
+        }
+    }
+
     protected override async void OnFolderDeleted(MailItemFolder folder)
     {
         base.OnFolderDeleted(folder);
@@ -1648,4 +1867,5 @@ public partial class MailListPageViewModel : MailBaseViewModel,
         var package = new MailOperationPreperationRequest(message.Operation, mailCopies);
         await ExecuteMailOperationAsync(package);
     }
+
 }

Wino.Mail.ViewModels/MailRenderingPageViewModel.cs

@@ -667,6 +667,23 @@ public partial class MailRenderingPageViewModel : MailBaseViewModel,
         await ExecuteUIThread(() => { InitializeCommandBarItems(); });
     }
 
+    protected override async void OnMailStateUpdated(MailStateChange updatedState, EntityUpdateSource source)
+    {
+        base.OnMailStateUpdated(updatedState, source);
+
+        if (initializedMailItemViewModel == null || updatedState == null)
+            return;
+
+        if (initializedMailItemViewModel.MailCopy.UniqueId != updatedState.UniqueId)
+            return;
+
+        await ExecuteUIThread(() =>
+        {
+            initializedMailItemViewModel.ApplyStateChanges(updatedState.IsRead, updatedState.IsFlagged);
+            InitializeCommandBarItems();
+        });
+    }
+
     protected override async void OnMailRemoved(MailCopy removedMail, EntityUpdateSource source)
     {
         base.OnMailRemoved(removedMail, source);

Wino.Mail.WinUI/Services/NotificationBuilder.cs

@@ -58,7 +58,12 @@ public class NotificationBuilder : INotificationBuilder
 
         WeakReferenceMessenger.Default.Register<MailReadStatusChanged>(this, (r, msg) =>
         {
-            RemoveNotification(msg.UniqueId);
+            QueueRemoveNotifications([msg.UniqueId]);
+        });
+
+        WeakReferenceMessenger.Default.Register<BulkMailReadStatusChanged>(this, (r, msg) =>
+        {
+            QueueRemoveNotifications(msg.UniqueIds);
         });
     }
 
@@ -156,16 +161,37 @@ public class NotificationBuilder : INotificationBuilder
 
     public void RemoveNotification(Guid mailUniqueId)
     {
-        try
+        QueueRemoveNotifications([mailUniqueId]);
+    }
+
+    private void QueueRemoveNotifications(IEnumerable<Guid> mailUniqueIds)
+    {
+        var uniqueIds = mailUniqueIds?
+            .Where(x => x != Guid.Empty)
+            .Distinct()
+            .ToList();
+
+        if (uniqueIds == null || uniqueIds.Count == 0)
+            return;
+
+        _ = RemoveNotificationsAsync(uniqueIds);
+    }
+
+    private static async Task RemoveNotificationsAsync(IReadOnlyList<Guid> mailUniqueIds)
+    {
+        foreach (var mailUniqueId in mailUniqueIds)
         {
-            AppNotificationManager.Default.RemoveByTagAsync(mailUniqueId.ToString()).AsTask().GetAwaiter().GetResult();
-        }
-        catch (ArgumentException)
-        {
-        }
-        catch (Exception ex)
-        {
-            Log.Error(ex, $"Failed to remove notification for mail {mailUniqueId}");
+            try
+            {
+                await AppNotificationManager.Default.RemoveByTagAsync(mailUniqueId.ToString()).AsTask().ConfigureAwait(false);
+            }
+            catch (ArgumentException)
+            {
+            }
+            catch (Exception ex)
+            {
+                Log.Error(ex, "Failed to remove notification for mail {MailUniqueId}", mailUniqueId);
+            }
         }
     }
 

Wino.Messages/UI/BulkMailAddedMessage.cs

@@ -0,0 +1,7 @@
+using System.Collections.Generic;
+using Wino.Core.Domain.Entities.Mail;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Messaging.UI;
+
+public record BulkMailAddedMessage(IReadOnlyList<MailCopy> AddedMails, EntityUpdateSource Source = EntityUpdateSource.Server) : UIMessageBase<BulkMailAddedMessage>;

Wino.Messages/UI/BulkMailReadStatusChanged.cs

@@ -0,0 +1,6 @@
+using System;
+using System.Collections.Generic;
+
+namespace Wino.Messaging.UI;
+
+public record BulkMailReadStatusChanged(IReadOnlyList<Guid> UniqueIds);

Wino.Messages/UI/BulkMailRemovedMessage.cs

@@ -0,0 +1,7 @@
+using System.Collections.Generic;
+using Wino.Core.Domain.Entities.Mail;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Messaging.UI;
+
+public record BulkMailRemovedMessage(IReadOnlyList<MailCopy> RemovedMails, EntityUpdateSource Source = EntityUpdateSource.Server) : UIMessageBase<BulkMailRemovedMessage>;

Wino.Messages/UI/BulkMailStateUpdatedMessage.cs

@@ -0,0 +1,8 @@
+using System.Collections.Generic;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Messaging.UI;
+
+public record BulkMailStateUpdatedMessage(
+    IReadOnlyList<MailStateChange> UpdatedStates,
+    EntityUpdateSource Source = EntityUpdateSource.Server) : UIMessageBase<BulkMailStateUpdatedMessage>;

Wino.Messages/UI/BulkMailUpdatedMessage.cs

@@ -1,6 +1,10 @@
 using System.Collections.Generic;
 using Wino.Core.Domain.Entities.Mail;
+using Wino.Core.Domain.Enums;
 
 namespace Wino.Messaging.UI;
 
-public record BulkMailUpdatedMessage(IReadOnlyList<MailCopy> UpdatedMails) : UIMessageBase<BulkMailUpdatedMessage>;
+public record BulkMailUpdatedMessage(
+    IReadOnlyList<MailCopy> UpdatedMails,
+    EntityUpdateSource Source = EntityUpdateSource.Server,
+    MailCopyChangeFlags ChangedProperties = MailCopyChangeFlags.None) : UIMessageBase<BulkMailUpdatedMessage>;

Wino.Messages/UI/MailStateChange.cs

@@ -0,0 +1,11 @@
+using System;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Messaging.UI;
+
+public sealed record MailStateChange(Guid UniqueId, bool? IsRead = null, bool? IsFlagged = null)
+{
+    public MailCopyChangeFlags ChangedProperties =>
+        (IsRead.HasValue ? MailCopyChangeFlags.IsRead : MailCopyChangeFlags.None) |
+        (IsFlagged.HasValue ? MailCopyChangeFlags.IsFlagged : MailCopyChangeFlags.None);
+}

Wino.Messages/UI/MailStateUpdatedMessage.cs

@@ -0,0 +1,7 @@
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Messaging.UI;
+
+public record MailStateUpdatedMessage(
+    MailStateChange UpdatedState,
+    EntityUpdateSource Source = EntityUpdateSource.Server) : UIMessageBase<MailStateUpdatedMessage>;

Wino.Services/MailService.cs

@@ -517,6 +517,53 @@ public class MailService : BaseDatabaseService, IMailService
         }
     }
 
+    private async Task PopulateAssignedPropertiesAsync(List<MailCopy> mails)
+    {
+        if (mails == null || mails.Count == 0)
+            return;
+
+        var folderIds = mails
+            .Select(m => m.FolderId)
+            .Distinct()
+            .ToList();
+
+        if (folderIds.Count == 0)
+            return;
+
+        var folders = await Task.WhenAll(folderIds.Select(id => _folderService.GetFolderAsync(id))).ConfigureAwait(false);
+        var folderCache = folders
+            .Where(f => f != null)
+            .ToDictionary(f => f.Id);
+
+        if (folderCache.Count == 0)
+            return;
+
+        var accountIds = folderCache.Values
+            .Select(f => f.MailAccountId)
+            .Distinct()
+            .ToHashSet();
+
+        var allAccounts = await _accountService.GetAccountsAsync().ConfigureAwait(false);
+        var accountCache = allAccounts
+            .Where(a => accountIds.Contains(a.Id))
+            .ToDictionary(a => a.Id);
+
+        var addresses = mails
+            .Where(m => !string.IsNullOrEmpty(m.FromAddress))
+            .Select(m => m.FromAddress)
+            .Distinct()
+            .ToList();
+
+        var contactCache = addresses.Count == 0
+            ? new Dictionary<string, AccountContact>()
+            : (await _contactService.GetContactsByAddressesAsync(addresses).ConfigureAwait(false))
+                .Where(c => c != null)
+                .ToDictionary(c => c.Address);
+
+        AssignPropertiesFromCaches(mails, folderCache, accountCache, contactCache);
+        await _sentMailReceiptService.PopulateReceiptStatesAsync(mails).ConfigureAwait(false);
+    }
+
     private async Task<List<MailCopy>> GetMailsByThreadIdsAsync(List<string> threadIds, HashSet<string> excludeMailIds)
     {
         if (threadIds?.Count == 0)
@@ -565,11 +612,34 @@ public class MailService : BaseDatabaseService, IMailService
 
     private async Task<List<MailCopy>> GetMailItemsAsync(string mailCopyId)
     {
-        var mailCopies = await Connection.Table<MailCopy>().Where(a => a.Id == mailCopyId).ToListAsync();
+        var mailCopies = await GetMailCopiesByIdAsync([mailCopyId]).ConfigureAwait(false);
+        await PopulateAssignedPropertiesAsync(mailCopies).ConfigureAwait(false);
 
-        foreach (var mailCopy in mailCopies)
+        return mailCopies;
+    }
+
+    private async Task<List<MailCopy>> GetMailCopiesByIdAsync(IEnumerable<string> mailCopyIds)
+    {
+        var distinctMailCopyIds = mailCopyIds?
+            .Where(a => !string.IsNullOrWhiteSpace(a))
+            .Distinct(StringComparer.Ordinal)
+            .ToList();
+
+        if (distinctMailCopyIds == null || distinctMailCopyIds.Count == 0)
+            return [];
+
+        var mailCopies = new List<MailCopy>();
+
+        const int batchSize = 200;
+
+        for (int i = 0; i < distinctMailCopyIds.Count; i += batchSize)
         {
-            await LoadAssignedPropertiesAsync(mailCopy).ConfigureAwait(false);
+            var batchIds = distinctMailCopyIds.Skip(i).Take(batchSize).ToList();
+            var placeholders = string.Join(",", batchIds.Select(_ => "?"));
+            var sql = $"SELECT * FROM MailCopy WHERE Id IN ({placeholders})";
+
+            var batch = await Connection.QueryAsync<MailCopy>(sql, batchIds.Cast<object>().ToArray()).ConfigureAwait(false);
+            mailCopies.AddRange(batch);
         }
 
         return mailCopies;
@@ -754,9 +824,51 @@ public class MailService : BaseDatabaseService, IMailService
 
     #endregion
 
-    private async Task UpdateAllMailCopiesAsync(string mailCopyId, Func<MailCopy, bool> action)
+    private async Task PersistMailCopyUpdatesAsync(IReadOnlyList<(MailCopy MailCopy, MailCopyChangeFlags ChangedProperties)> pendingUpdates)
     {
-        var mailCopies = await GetMailItemsAsync(mailCopyId);
+        if (pendingUpdates == null || pendingUpdates.Count == 0)
+            return;
+
+        await Connection.RunInTransactionAsync(connection =>
+        {
+            foreach (var (mailCopy, _) in pendingUpdates)
+            {
+                connection.Update(mailCopy, typeof(MailCopy));
+            }
+        }).ConfigureAwait(false);
+
+        var readMailUniqueIds = pendingUpdates
+            .Where(x => (x.ChangedProperties & MailCopyChangeFlags.IsRead) != 0 &&
+                        x.MailCopy?.IsRead == true &&
+                        x.MailCopy.UniqueId != Guid.Empty)
+            .Select(x => x.MailCopy.UniqueId)
+            .Distinct()
+            .ToList();
+
+        if (readMailUniqueIds.Count > 0)
+        {
+            WeakReferenceMessenger.Default.Send(new BulkMailReadStatusChanged(readMailUniqueIds));
+        }
+
+        foreach (var updateGroup in pendingUpdates
+                     .Where(x => x.MailCopy != null)
+                     .GroupBy(x => x.ChangedProperties))
+        {
+            var updatedMails = updateGroup
+                .Select(x => x.MailCopy)
+                .Where(x => x != null)
+                .ToList();
+
+            if (updatedMails.Count == 0)
+                continue;
+
+            ReportUIChange(new BulkMailUpdatedMessage(updatedMails, EntityUpdateSource.Server, updateGroup.Key));
+        }
+    }
+
+    private async Task UpdateAllMailCopiesAsync(string mailCopyId, Func<MailCopy, MailCopyChangeFlags> action)
+    {
+        var mailCopies = await GetMailCopiesByIdAsync([mailCopyId]).ConfigureAwait(false);
 
         if (mailCopies == null || !mailCopies.Any())
         {
@@ -767,43 +879,110 @@ public class MailService : BaseDatabaseService, IMailService
 
         _logger.Debug("Updating {MailCopyCount} mail copies with Id {MailCopyId}", mailCopies.Count, mailCopyId);
 
+        var pendingUpdates = new List<(MailCopy MailCopy, MailCopyChangeFlags ChangedProperties)>();
+
         foreach (var mailCopy in mailCopies)
         {
-            bool shouldUpdateItem = action(mailCopy);
+            var changedProperties = action(mailCopy);
 
-            if (shouldUpdateItem)
+            if (changedProperties != MailCopyChangeFlags.None)
             {
-                await UpdateMailAsync(mailCopy).ConfigureAwait(false);
+                pendingUpdates.Add((mailCopy, changedProperties));
             }
             else
+            {
                 _logger.Debug("Skipped updating mail because it is already in the desired state.");
+            }
         }
+
+        await PersistMailCopyUpdatesAsync(pendingUpdates).ConfigureAwait(false);
     }
 
     public Task ChangeReadStatusAsync(string mailCopyId, bool isRead)
         => UpdateAllMailCopiesAsync(mailCopyId, (item) =>
         {
-            if (item.IsRead == isRead) return false;
+            if (item.IsRead == isRead) return MailCopyChangeFlags.None;
 
             item.IsRead = isRead;
-            if (isRead && item.UniqueId != Guid.Empty)
-            {
-                WeakReferenceMessenger.Default.Send(new MailReadStatusChanged(item.UniqueId));
-            }
 
-            return true;
+            return MailCopyChangeFlags.IsRead;
         });
 
     public Task ChangeFlagStatusAsync(string mailCopyId, bool isFlagged)
         => UpdateAllMailCopiesAsync(mailCopyId, (item) =>
         {
-            if (item.IsFlagged == isFlagged) return false;
+            if (item.IsFlagged == isFlagged) return MailCopyChangeFlags.None;
 
             item.IsFlagged = isFlagged;
 
-            return true;
+            return MailCopyChangeFlags.IsFlagged;
         });
 
+    public async Task ApplyMailStateUpdatesAsync(IEnumerable<MailCopyStateUpdate> updates)
+    {
+        var updateLookup = new Dictionary<string, MailCopyStateUpdate>(StringComparer.Ordinal);
+
+        foreach (var update in updates ?? [])
+        {
+            if (update == null || string.IsNullOrWhiteSpace(update.MailCopyId))
+                continue;
+
+            if (updateLookup.TryGetValue(update.MailCopyId, out var existingUpdate))
+            {
+                updateLookup[update.MailCopyId] = new MailCopyStateUpdate(
+                    update.MailCopyId,
+                    update.IsRead ?? existingUpdate.IsRead,
+                    update.IsFlagged ?? existingUpdate.IsFlagged);
+            }
+            else
+            {
+                updateLookup[update.MailCopyId] = update;
+            }
+        }
+
+        if (updateLookup.Count == 0)
+            return;
+
+        var mailCopies = await GetMailCopiesByIdAsync(updateLookup.Keys).ConfigureAwait(false);
+
+        if (mailCopies.Count == 0)
+        {
+            _logger.Warning("Applying mail state updates failed because there are no matching copies for {MailCopyCount} ids.", updateLookup.Count);
+            return;
+        }
+
+        await PopulateAssignedPropertiesAsync(mailCopies).ConfigureAwait(false);
+
+        var pendingUpdates = new List<(MailCopy MailCopy, MailCopyChangeFlags ChangedProperties)>();
+
+        foreach (var mailCopy in mailCopies)
+        {
+            if (!updateLookup.TryGetValue(mailCopy.Id, out var update))
+                continue;
+
+            var changedProperties = MailCopyChangeFlags.None;
+
+            if (update.IsRead.HasValue && mailCopy.IsRead != update.IsRead.Value)
+            {
+                mailCopy.IsRead = update.IsRead.Value;
+                changedProperties |= MailCopyChangeFlags.IsRead;
+            }
+
+            if (update.IsFlagged.HasValue && mailCopy.IsFlagged != update.IsFlagged.Value)
+            {
+                mailCopy.IsFlagged = update.IsFlagged.Value;
+                changedProperties |= MailCopyChangeFlags.IsFlagged;
+            }
+
+            if (changedProperties != MailCopyChangeFlags.None)
+            {
+                pendingUpdates.Add((mailCopy, changedProperties));
+            }
+        }
+
+        await PersistMailCopyUpdatesAsync(pendingUpdates).ConfigureAwait(false);
+    }
+
     public async Task CreateAssignmentAsync(Guid accountId, string mailCopyId, string remoteFolderId)
     {
         // Note: Folder might not be available at the moment due to user not syncing folders before the delta processing.
@@ -1396,18 +1575,26 @@ public class MailService : BaseDatabaseService, IMailService
                 (shouldUpdateDraftId && item.DraftId != newDraftId))
             {
                 var oldDraftId = item.DraftId;
+                var changedProperties = MailCopyChangeFlags.None;
 
                 if (shouldUpdateDraftId)
+                {
                     item.DraftId = newDraftId;
+                    changedProperties |= MailCopyChangeFlags.DraftId;
+                }
+
                 if (shouldUpdateThreadId)
+                {
                     item.ThreadId = newThreadId;
+                    changedProperties |= MailCopyChangeFlags.ThreadId;
+                }
 
                 ReportUIChange(new DraftMapped(oldDraftId, item.DraftId));
 
-                return true;
+                return changedProperties;
             }
 
-            return false;
+            return MailCopyChangeFlags.None;
         });
     }