Some experiments.

Wino.Mail.ViewModels/Collections/WinoMailCollection.cs

@@ -444,7 +444,7 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
 
         await ExecuteUIThread(() =>
         {
-            existingItem.MailCopy = updatedItem;
+            existingItem.UpdateFrom(updatedItem);
         });
 
         UpdateUniqueIdHashes(existingItem, true);
@@ -574,7 +574,7 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
                 foreach (var (existing, updated) in itemsToUpdate)
                 {
                     UpdateUniqueIdHashes(existing, false);
-                    existing.MailCopy = updated;
+                    existing.UpdateFrom(updated);
                     UpdateUniqueIdHashes(existing, true);
                 }
             });
@@ -720,7 +720,7 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
     }
 
     /// <summary>
-    /// Fins the item container that updated mail copy belongs to and updates it.
+    /// Finds the item container that updated mail copy belongs to and updates it.
     /// </summary>
     /// <param name="updatedMailCopy">Updated mail copy.</param>
     /// <returns></returns>
@@ -739,8 +739,9 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
             {
                 UpdateUniqueIdHashes(itemContainer.ItemViewModel, false);
 
-                // Update the MailCopy - this will automatically notify all dependent properties
-                itemContainer.ItemViewModel.MailCopy = updatedMailCopy;
+                // Update the MailCopy using UpdateFrom to properly notify all XAML bindings
+                // This maintains reference integrity and ensures PropertyChanged is raised for all properties
+                itemContainer.ItemViewModel.UpdateFrom(updatedMailCopy);
 
                 UpdateUniqueIdHashes(itemContainer.ItemViewModel, true);
             }
@@ -748,7 +749,7 @@ public class WinoMailCollection : ObservableRecipient, IRecipient<SelectedItemsC
             // Trigger thread property notifications if this item is in a thread
             if (itemContainer.ThreadViewModel != null)
             {
-                itemContainer.ThreadViewModel.ThreadEmails = itemContainer.ThreadViewModel.ThreadEmails;
+                itemContainer.ThreadViewModel.NotifyMailItemUpdated(itemContainer.ItemViewModel);
             }
         });
     }

Wino.Mail.ViewModels/ComposePageViewModel.cs

@@ -643,7 +643,7 @@ public partial class ComposePageViewModel : MailBaseViewModel
         {
             await ExecuteUIThread(() =>
             {
-                CurrentMailDraftItem.MailCopy = updatedMail;
+                CurrentMailDraftItem.UpdateFrom(updatedMail);
                 DiscardCommand.NotifyCanExecuteChanged();
                 SendCommand.NotifyCanExecuteChanged();
             });

Wino.Mail.ViewModels/Data/MailItemViewModel.cs

@@ -184,4 +184,67 @@ public partial class MailItemViewModel(MailCopy mailCopy) : ObservableRecipient,
             yield return this;
         }
     }
+
+    /// <summary>
+    /// Updates the MailCopy with new data and notifies all bound properties.
+    /// This method copies values from the source to the existing MailCopy to maintain reference integrity,
+    /// then explicitly raises PropertyChanged for all dependent properties.
+    /// </summary>
+    /// <param name="source">The source MailCopy with updated values.</param>
+    public void UpdateFrom(MailCopy source)
+    {
+        if (source == null) return;
+
+        // Update the underlying MailCopy properties directly to maintain reference integrity
+        // This is important because other parts of the app may hold references to this MailCopy
+        // Note: UniqueId is the primary key and should match - we don't update it
+        MailCopy.Id = source.Id;
+        MailCopy.FolderId = source.FolderId;
+        MailCopy.ThreadId = source.ThreadId;
+        MailCopy.MessageId = source.MessageId;
+        MailCopy.References = source.References;
+        MailCopy.InReplyTo = source.InReplyTo;
+        MailCopy.IsDraft = source.IsDraft;
+        MailCopy.DraftId = source.DraftId;
+        MailCopy.CreationDate = source.CreationDate;
+        MailCopy.Subject = source.Subject;
+        MailCopy.PreviewText = source.PreviewText;
+        MailCopy.FromName = source.FromName;
+        MailCopy.FromAddress = source.FromAddress;
+        MailCopy.HasAttachments = source.HasAttachments;
+        MailCopy.Importance = source.Importance;
+        MailCopy.IsRead = source.IsRead;
+        MailCopy.IsFlagged = source.IsFlagged;
+        MailCopy.IsFocused = source.IsFocused;
+        MailCopy.FileId = source.FileId;
+        MailCopy.ItemType = source.ItemType;
+        MailCopy.SenderContact = source.SenderContact;
+        MailCopy.AssignedAccount = source.AssignedAccount;
+        MailCopy.AssignedFolder = source.AssignedFolder;
+
+        // Raise PropertyChanged for all properties that XAML may bind to
+        OnPropertyChanged(nameof(CreationDate));
+        OnPropertyChanged(nameof(IsFlagged));
+        OnPropertyChanged(nameof(FromName));
+        OnPropertyChanged(nameof(IsFocused));
+        OnPropertyChanged(nameof(IsRead));
+        OnPropertyChanged(nameof(IsDraft));
+        OnPropertyChanged(nameof(DraftId));
+        OnPropertyChanged(nameof(Id));
+        OnPropertyChanged(nameof(Subject));
+        OnPropertyChanged(nameof(PreviewText));
+        OnPropertyChanged(nameof(FromAddress));
+        OnPropertyChanged(nameof(HasAttachments));
+        OnPropertyChanged(nameof(Importance));
+        OnPropertyChanged(nameof(ThreadId));
+        OnPropertyChanged(nameof(MessageId));
+        OnPropertyChanged(nameof(References));
+        OnPropertyChanged(nameof(InReplyTo));
+        OnPropertyChanged(nameof(FileId));
+        OnPropertyChanged(nameof(FolderId));
+        OnPropertyChanged(nameof(UniqueId));
+        OnPropertyChanged(nameof(Base64ContactPicture));
+        OnPropertyChanged(nameof(SortingDate));
+        OnPropertyChanged(nameof(SortingName));
+    }
 }

Wino.Mail.ViewModels/Data/ThreadMailItemViewModel.cs

@@ -213,6 +213,40 @@ public partial class ThreadMailItemViewModel : ObservableRecipient, IMailListIte
         }
     }
 
+    /// <summary>
+    /// Notifies that a mail item within this thread has been updated.
+    /// This raises PropertyChanged for all thread-level computed properties that depend on child items.
+    /// </summary>
+    /// <param name="updatedMailItem">The mail item that was updated (can be null to refresh all).</param>
+    public void NotifyMailItemUpdated(MailItemViewModel updatedMailItem)
+    {
+        // Raise PropertyChanged for all computed properties that depend on ThreadEmails contents
+        OnPropertyChanged(nameof(Subject));
+        OnPropertyChanged(nameof(FromName));
+        OnPropertyChanged(nameof(CreationDate));
+        OnPropertyChanged(nameof(FromAddress));
+        OnPropertyChanged(nameof(PreviewText));
+        OnPropertyChanged(nameof(HasAttachments));
+        OnPropertyChanged(nameof(IsFlagged));
+        OnPropertyChanged(nameof(IsFocused));
+        OnPropertyChanged(nameof(IsRead));
+        OnPropertyChanged(nameof(IsDraft));
+        OnPropertyChanged(nameof(DraftId));
+        OnPropertyChanged(nameof(Id));
+        OnPropertyChanged(nameof(Importance));
+        OnPropertyChanged(nameof(ThreadId));
+        OnPropertyChanged(nameof(MessageId));
+        OnPropertyChanged(nameof(References));
+        OnPropertyChanged(nameof(InReplyTo));
+        OnPropertyChanged(nameof(FileId));
+        OnPropertyChanged(nameof(FolderId));
+        OnPropertyChanged(nameof(UniqueId));
+        OnPropertyChanged(nameof(Base64ContactPicture));
+        OnPropertyChanged(nameof(ThumbnailUpdatedEvent));
+        OnPropertyChanged(nameof(SortingDate));
+        OnPropertyChanged(nameof(SortingName));
+    }
+
     /// <summary>
     /// Checks if this thread contains an email with the specified unique ID
     /// </summary>

Wino.Mail.ViewModels/MailListPageViewModel.cs

@@ -668,8 +668,6 @@ public partial class MailListPageViewModel : MailBaseViewModel,
     {
         base.OnMailUpdated(updatedMail);
 
-        Debug.WriteLine($"Updating {updatedMail.Id}-> {updatedMail.UniqueId}");
-
         await MailCollection.UpdateMailCopy(updatedMail);
 
         await ExecuteUIThread(() => { SetupTopBarActions(); });