SSL Handshake Prompt for IMAP (#381)

* Fix an incorrect namespace for copy auth url request.

* Implemented SSL handshake process for testing imap configuration.

* Implemented SSL handshake process for testing imap configuration.

* Replace certificate PathIcon with WinoFontIcon in XAML.

Wino.Core.Domain/Exceptions/ImapConnectionFailedPackage.cs

@@ -1,21 +1,18 @@
-using System;
+using Wino.Core.Domain.Models.AutoDiscovery;
-using Wino.Core.Domain.Models.AutoDiscovery;
 
 namespace Wino.Core.Domain.Exceptions
 {
     public class ImapConnectionFailedPackage
     {
-        public ImapConnectionFailedPackage(Exception error, string protocolLog, AutoDiscoverySettings settings)
+        public ImapConnectionFailedPackage(string errorMessage, string protocolLog, AutoDiscoverySettings settings)
         {
-            Error = error;
+            ErrorMessage = errorMessage;
             ProtocolLog = protocolLog;
             Settings = settings;
         }
 
         public AutoDiscoverySettings Settings { get; }
-        public Exception Error { get; }
+        public string ErrorMessage { get; set; }
         public string ProtocolLog { get; }
-
-        public string GetErrorMessage() => Error.InnerException == null ? Error.Message : Error.InnerException.Message;
     }
 }

Wino.Core.Domain/Exceptions/ImapTestSSLCertificateException.cs

@@ -0,0 +1,17 @@
+namespace Wino.Core.Domain.Exceptions
+{
+    public class ImapTestSSLCertificateException : System.Exception
+    {
+        public ImapTestSSLCertificateException(string issuer, string expirationDateString, string validFromDateString)
+        {
+            Issuer = issuer;
+            ExpirationDateString = expirationDateString;
+            ValidFromDateString = validFromDateString;
+        }
+
+        public string Issuer { get; set; }
+        public string ExpirationDateString { get; set; }
+        public string ValidFromDateString { get; set; }
+
+    }
+}

Wino.Core.Domain/Extensions/ExceptionExtensions.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+
+namespace Wino.Core.Domain.Extensions
+{
+    public static class ExceptionExtensions
+    {
+        public static IEnumerable<Exception> GetInnerExceptions(this Exception ex)
+        {
+            if (ex == null)
+            {
+                throw new ArgumentNullException("ex");
+            }
+
+            var innerException = ex;
+            do
+            {
+                yield return innerException;
+                innerException = innerException.InnerException;
+            }
+            while (innerException != null);
+        }
+    }
+}

Wino.Core.Domain/Interfaces/IImapTestService.cs

@@ -5,6 +5,6 @@ namespace Wino.Core.Domain.Interfaces
 {
     public interface IImapTestService
     {
-        Task TestImapConnectionAsync(CustomServerInformation serverInformation);
+        Task TestImapConnectionAsync(CustomServerInformation serverInformation, bool allowSSLHandShake);
     }
 }

Wino.Core.Domain/Models/Connectivity/ImapConnectivityTestResults.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Linq;
+using System.Text.Json.Serialization;
+using Wino.Core.Domain.Extensions;
+
+namespace Wino.Core.Domain.Models.Connectivity
+{
+    /// <summary>
+    /// Contains validation of the IMAP server connectivity during account setup.
+    /// </summary>
+    public class ImapConnectivityTestResults
+    {
+        [JsonConstructor]
+        protected ImapConnectivityTestResults() { }
+
+        public bool IsSuccess { get; set; }
+
+        public bool IsCertificateUIRequired { get; set; }
+
+        public string FailedReason { get; set; }
+        public string FailureProtocolLog { get; set; }
+
+        public static ImapConnectivityTestResults Success() => new ImapConnectivityTestResults() { IsSuccess = true };
+        public static ImapConnectivityTestResults Failure(Exception ex, string failureProtocolLog) => new ImapConnectivityTestResults()
+        {
+            FailedReason = string.Join(Environment.NewLine, ex.GetInnerExceptions().Select(e => e.Message)),
+            FailureProtocolLog = failureProtocolLog
+        };
+
+        public static ImapConnectivityTestResults CertificateUIRequired(string issuer,
+            string expirationString,
+            string validFromString)
+        {
+            return new ImapConnectivityTestResults()
+            {
+                IsSuccess = false,
+                IsCertificateUIRequired = true,
+                CertificateIssuer = issuer,
+                CertificateExpirationDateString = expirationString,
+                CertificateValidFromDateString = validFromString
+            };
+        }
+
+        public string CertificateIssuer { get; set; }
+        public string CertificateValidFromDateString { get; set; }
+        public string CertificateExpirationDateString { get; set; }
+    }
+}

Wino.Core.Domain/Translations/en_US/resources.json

@@ -34,6 +34,8 @@
     "BasicIMAPSetupDialog_Title": "IMAP Account",
     "Buttons_AddAccount": "Add Account",
     "Buttons_AddNewAlias": "Add New Alias",
+    "Buttons_Allow": "Allow",
+    "Buttons_Deny": "Deny",
     "Buttons_SyncAliases": "Synchronize Aliases",
     "Buttons_ApplyTheme": "Apply Theme",
     "Buttons_Browse": "Browse",
@@ -221,6 +223,14 @@
     "IMAPSetupDialog_UsernamePlaceholder": "johndoe, johndoe@fabrikam.com, domain/johndoe",
     "IMAPSetupDialog_ConnectionFailedTitle": "Connection Failed",
     "IMAPSetupDialog_ConnectionFailedMessage": "IMAP connection failed.",
+    "IMAPSetupDialog_CertificateAllowanceRequired_Row0": "This server is requesting a SSL handshake to continue. Please confirm the certificate details below.",
+    "IMAPSetupDialog_CertificateAllowanceRequired_Row1": "Allow the handshake to continue setting up your account.",
+    "IMAPSetupDialog_CertificateIssuer": "Issuer",
+    "IMAPSetupDialog_CertificateSubject": "Subject",
+    "IMAPSetupDialog_CertificateValidFrom": "Valid from",
+    "IMAPSetupDialog_CertificateValidTo": "Valid to",
+    "IMAPSetupDialog_CertificateDenied": "User didn't authorize the handshake with the certificate.",
+    "IMAPSetupDialog_CertificateView": "View Certificate",
     "ImageRenderingDisabled": "Image rendering is disabled for this message.",
     "InfoBarAction_Enable": "Enable",
     "InfoBarMessage_SynchronizationDisabledFolder": "This folder is disabled for synchronization.",

Wino.Core.Domain/Translator.Designer.cs

@@ -193,6 +193,16 @@ namespace Wino.Core.Domain
 		/// </summary>
 		public static string Buttons_AddNewAlias => Resources.GetTranslatedString(@"Buttons_AddNewAlias");	
 	
+        /// <summary>
+		/// Allow
+		/// </summary>
+		public static string Buttons_Allow => Resources.GetTranslatedString(@"Buttons_Allow");	
+	
+        /// <summary>
+		/// Deny
+		/// </summary>
+		public static string Buttons_Deny => Resources.GetTranslatedString(@"Buttons_Deny");	
+	
         /// <summary>
 		/// Synchronize Aliases
 		/// </summary>
@@ -1128,6 +1138,46 @@ namespace Wino.Core.Domain
 		/// </summary>
 		public static string IMAPSetupDialog_ConnectionFailedMessage => Resources.GetTranslatedString(@"IMAPSetupDialog_ConnectionFailedMessage");	
 	
+        /// <summary>
+		/// This server is requesting a SSL handshake to continue. Please confirm the certificate details below.
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateAllowanceRequired_Row0 => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateAllowanceRequired_Row0");	
+	
+        /// <summary>
+		/// Allow the handshake to continue setting up your account.
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateAllowanceRequired_Row1 => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateAllowanceRequired_Row1");	
+	
+        /// <summary>
+		/// Issuer
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateIssuer => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateIssuer");	
+	
+        /// <summary>
+		/// Subject
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateSubject => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateSubject");	
+	
+        /// <summary>
+		/// Valid from
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateValidFrom => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateValidFrom");	
+	
+        /// <summary>
+		/// Valid to
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateValidTo => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateValidTo");	
+	
+        /// <summary>
+		/// User didn't authorize the handshake with the certificate.
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateDenied => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateDenied");	
+	
+        /// <summary>
+		/// View Certificate
+		/// </summary>
+		public static string IMAPSetupDialog_CertificateView => Resources.GetTranslatedString(@"IMAPSetupDialog_CertificateView");	
+	
         /// <summary>
 		/// Image rendering is disabled for this message.
 		/// </summary>

Wino.Core.UWP/Services/WinoServerConnectionManager.cs

@@ -18,7 +18,6 @@ using Wino.Core.Integration.Json;
 using Wino.Messaging;
 using Wino.Messaging.Client.Connection;
 using Wino.Messaging.Enums;
-using Wino.Messaging.Server;
 using Wino.Messaging.UI;
 
 namespace Wino.Core.UWP.Services

Wino.Core/Authenticators/GmailAuthenticator.cs

@@ -12,7 +12,7 @@ using Wino.Core.Domain.Interfaces;
 using Wino.Core.Domain.Models.Authentication;
 using Wino.Core.Domain.Models.Authorization;
 using Wino.Core.Services;
-using Wino.Messaging.Server;
+using Wino.Messaging.UI;
 
 namespace Wino.Core.Authenticators
 {

Wino.Core/Integration/ImapClientPool.cs

@@ -2,6 +2,8 @@
 using System.Collections.Concurrent;
 using System.IO;
 using System.Net;
+using System.Net.Security;
+using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
@@ -9,6 +11,7 @@ using MailKit;
 using MailKit.Net.Imap;
 using MailKit.Net.Proxy;
 using MailKit.Security;
+using MimeKit.Cryptography;
 using MoreLinq;
 using Serilog;
 using Wino.Core.Domain.Entities;
@@ -42,6 +45,8 @@ namespace Wino.Core.Integration
             Name = "Wino Mail User",
         };
 
+        public bool ThrowOnSSLHandshakeCallback { get; set; }
+
         private readonly int MinimumPoolSize = 5;
 
         private readonly ConcurrentStack<ImapClient> _clients = [];
@@ -57,6 +62,8 @@ namespace Wino.Core.Integration
 
             // Set the maximum pool size to 5 or the custom value if it's greater.
             _semaphore = new(Math.Max(MinimumPoolSize, customServerInformation.MaxConcurrentClients));
+
+            CryptographyContext.Register(typeof(WindowsSecureMimeContext));
         }
 
         private async Task EnsureConnectivityAsync(ImapClient client, bool isCreatedNew)
@@ -107,6 +114,9 @@ namespace Wino.Core.Integration
             }
             catch (Exception ex)
             {
+                if (ex.InnerException is ImapTestSSLCertificateException imapTestSSLCertificateException)
+                    throw imapTestSSLCertificateException;
+
                 throw new ImapClientPoolException(ex, GetProtocolLogContent());
             }
             finally
@@ -215,11 +225,27 @@ namespace Wino.Core.Integration
         {
             if (client.IsConnected) return;
 
+            client.ServerCertificateValidationCallback = MyServerCertificateValidationCallback;
+
             await client.ConnectAsync(_customServerInformation.IncomingServer,
                                       int.Parse(_customServerInformation.IncomingServerPort),
                                       GetSocketOptions(_customServerInformation.IncomingServerSocketOption));
         }
 
+        bool MyServerCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
+        {
+            // If there are no errors, then everything went smoothly.
+            if (sslPolicyErrors == SslPolicyErrors.None) return true;
+
+            // Imap connectivity test will throw to alert the user here.
+            if (ThrowOnSSLHandshakeCallback)
+            {
+                throw new ImapTestSSLCertificateException(certificate.Issuer, certificate.GetExpirationDateString(), certificate.GetEffectiveDateString());
+            }
+
+            return true;
+        }
+
         public async Task EnsureAuthenticatedAsync(ImapClient client)
         {
             if (client.IsAuthenticated) return;

Wino.Core/Services/ImapTestService.cs

@@ -34,11 +34,14 @@ namespace Wino.Core.Services
             _protocolLogStream = File.Create(logFile);
         }
 
-        public async Task TestImapConnectionAsync(CustomServerInformation serverInformation)
+        public async Task TestImapConnectionAsync(CustomServerInformation serverInformation, bool allowSSLHandShake)
         {
             EnsureProtocolLogFileExists();
 
-            var clientPool = new ImapClientPool(serverInformation, _protocolLogStream);
+            var clientPool = new ImapClientPool(serverInformation, _protocolLogStream)
+            {
+                ThrowOnSSLHandshakeCallback = !allowSSLHandShake
+            };
 
             using (clientPool)
             {

Wino.Mail/Dialogs/AccountCreationDialog.xaml.cs

@@ -3,7 +3,7 @@ using System.Threading.Tasks;
 using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.Extensions.DependencyInjection;
 using Wino.Core.Domain.Interfaces;
-using Wino.Messaging.Server;
+using Wino.Messaging.UI;
 
 namespace Wino.Dialogs
 {

Wino.Mail/Views/ImapSetup/AdvancedImapSetupPage.xaml

@@ -2,13 +2,13 @@
     x:Class="Wino.Views.ImapSetup.AdvancedImapSetupPage"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:domain="using:Wino.Core.Domain"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
-    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:domain="using:Wino.Core.Domain"
-    d:RequestedTheme="Dark"
     xmlns:helpers="using:Wino.Helpers"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:muxc="using:Microsoft.UI.Xaml.Controls"
     d:Background="Black"
+    d:RequestedTheme="Dark"
     mc:Ignorable="d">
 
     <Grid RowSpacing="4">
@@ -18,31 +18,31 @@
         </Grid.RowDefinitions>
 
         <ScrollViewer x:Name="MainScrollviewer" Padding="{StaticResource ImapSetupDialogSubPagePadding}">
-            <StackPanel Spacing="12" Padding="0,0,16,0">
+            <StackPanel Padding="0,0,16,0" Spacing="12">
                 <TextBlock
-                    d:Text="Advanced IMAP / SMTP Configuration"
-                    Text="{x:Bind domain:Translator.IMAPSetupDialog_Title}"
                     Margin="1,0,0,0"
-                    Style="{StaticResource TitleTextBlockStyle}" />
+                    d:Text="Advanced IMAP / SMTP Configuration"
+                    Style="{StaticResource TitleTextBlockStyle}"
+                    Text="{x:Bind domain:Translator.IMAPSetupDialog_Title}" />
 
                 <TextBox
+                    x:Name="AddressBox"
                     d:Header="Mail"
                     Header="{x:Bind domain:Translator.IMAPSetupDialog_MailAddress}"
-                    PlaceholderText="{x:Bind domain:Translator.IMAPSetupDialog_MailAddressPlaceholder}"
+                    PlaceholderText="{x:Bind domain:Translator.IMAPSetupDialog_MailAddressPlaceholder}" />
-                    x:Name="AddressBox" />
 
                 <TextBox
+                    x:Name="DisplayNameBox"
                     d:Header="Display Name"
                     Header="{x:Bind domain:Translator.IMAPSetupDialog_DisplayName}"
-                    PlaceholderText="{x:Bind domain:Translator.IMAPSetupDialog_DisplayNamePlaceholder}"
+                    PlaceholderText="{x:Bind domain:Translator.IMAPSetupDialog_DisplayNamePlaceholder}" />
-                    x:Name="DisplayNameBox" />
 
                 <CheckBox Content="{x:Bind domain:Translator.IMAPSetupDialog_UseSameConfig}" IsChecked="{x:Bind UseSameCredentialsForSending, Mode=TwoWay}" />
 
                 <muxc:TabView
                     d:SelectedIndex="0"
-                    IsAddTabButtonVisible="False"
                     CanReorderTabs="False"
+                    IsAddTabButtonVisible="False"
                     TabWidthMode="Equal">
                     <muxc:TabViewItem Header="IMAP Settings" IsClosable="False">
                         <!--  IMAP  -->
@@ -55,34 +55,34 @@
                                 </Grid.ColumnDefinitions>
 
                                 <TextBox
+                                    x:Name="IncomingServerBox"
                                     d:Header="Incoming Server"
-                                    TextChanged="IncomingServerChanged"
-                                    PlaceholderText="eg. imap.gmail.com"
                                     Header="{x:Bind domain:Translator.IMAPSetupDialog_IncomingMailServer}"
-                                    x:Name="IncomingServerBox" />
+                                    PlaceholderText="eg. imap.gmail.com"
+                                    TextChanged="IncomingServerChanged" />
 
                                 <TextBox
-                                    d:Header="Port"
-                                    Text="993"
-                                    Header="{x:Bind domain:Translator.IMAPSetupDialog_IncomingMailServerPort}"
                                     x:Name="IncomingServerPortBox"
-                                    Grid.Column="1" />
+                                    Grid.Column="1"
+                                    d:Header="Port"
+                                    Header="{x:Bind domain:Translator.IMAPSetupDialog_IncomingMailServerPort}"
+                                     />
                             </Grid>
 
                             <!--  Username + Password  -->
                             <StackPanel Spacing="6">
                                 <TextBox
+                                    x:Name="UsernameBox"
                                     d:Header="Username"
-                                    TextChanged="IncomingUsernameChanged"
                                     Header="{x:Bind domain:Translator.IMAPSetupDialog_Username}"
                                     PlaceholderText="{x:Bind domain:Translator.IMAPSetupDialog_UsernamePlaceholder}"
-                                    x:Name="UsernameBox" />
+                                    TextChanged="IncomingUsernameChanged" />
 
                                 <PasswordBox
-                                    PasswordChanged="IncomingPasswordChanged"
+                                    x:Name="PasswordBox"
                                     d:Header="Password"
                                     Header="{x:Bind domain:Translator.IMAPSetupDialog_Password}"
-                                    x:Name="PasswordBox" />
+                                    PasswordChanged="IncomingPasswordChanged" />
                             </StackPanel>
 
                             <!--  Security and Authentication  -->
@@ -94,35 +94,35 @@
                                 <!--  Security  -->
                                 <StackPanel Spacing="6">
                                     <TextBlock
+                                        HorizontalAlignment="Center"
                                         d:Text="Connection security"
-                                        Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_ConnectionSecurity}"
+                                        Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_ConnectionSecurity}" />
-                                        HorizontalAlignment="Center" />
                                     <ComboBox
                                         x:Name="IncomingConnectionSecurity"
-                                        SelectedIndex="0"
                                         HorizontalAlignment="Stretch"
+                                        DisplayMemberPath="DisplayName"
                                         ItemsSource="{x:Bind AvailableConnectionSecurities}"
-                                        DisplayMemberPath="DisplayName" />
+                                        SelectedIndex="0" />
                                 </StackPanel>
 
                                 <!--  Authentication  -->
                                 <StackPanel Grid.Column="1" Spacing="6">
                                     <TextBlock
+                                        HorizontalAlignment="Center"
                                         d:Text="Authentication method"
-                                        Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_AuthenticationMethod}"
+                                        Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_AuthenticationMethod}" />
-                                        HorizontalAlignment="Center" />
                                     <ComboBox
                                         x:Name="IncomingAuthenticationMethod"
-                                        SelectedIndex="0"
                                         HorizontalAlignment="Stretch"
+                                        DisplayMemberPath="DisplayName"
                                         ItemsSource="{x:Bind AvailableAuthenticationMethods}"
-                                        DisplayMemberPath="DisplayName" />
+                                        SelectedIndex="0" />
                                 </StackPanel>
                             </Grid>
 
                         </StackPanel>
                     </muxc:TabViewItem>
-                    <muxc:TabViewItem IsClosable="False" Header="SMTP Settings">
+                    <muxc:TabViewItem Header="SMTP Settings" IsClosable="False">
                         <!--  SMTP  -->
                         <StackPanel Padding="12" Spacing="10">
                             <!--  Server + Port  -->
@@ -133,18 +133,18 @@
                                 </Grid.ColumnDefinitions>
 
                                 <TextBox
+                                    x:Name="OutgoingServerBox"
                                     d:Header="Outgoing Server"
-                                    TextChanged="OutgoingServerChanged"
-                                    PlaceholderText="eg. smtp.gmail.com"
                                     Header="{x:Bind domain:Translator.IMAPSetupDialog_OutgoingMailServer}"
-                                    x:Name="OutgoingServerBox" />
+                                    PlaceholderText="eg. smtp.gmail.com"
+                                    TextChanged="OutgoingServerChanged" />
 
                                 <TextBox
+                                    x:Name="OutgoingServerPort"
+                                    Grid.Column="1"
                                     d:Header="Port"
                                     Header="{x:Bind domain:Translator.IMAPSetupDialog_OutgoingMailServerPort}"
-                                    x:Name="OutgoingServerPort"
+                                     />
-                                    Text="587"
-                                    Grid.Column="1" />
                             </Grid>
 
                             <!--  Username + Password  -->
@@ -152,13 +152,13 @@
                                 <TextBox
                                     x:Name="OutgoingUsernameBox"
                                     d:Header="UserName"
-                                    IsEnabled="{x:Bind helpers:XamlHelpers.ReverseBoolConverter(UseSameCredentialsForSending), Mode=OneWay}"
+                                    Header="{x:Bind domain:Translator.IMAPSetupDialog_OutgoingMailServerUsername}"
-                                    Header="{x:Bind domain:Translator.IMAPSetupDialog_OutgoingMailServerUsername}" />
+                                    IsEnabled="{x:Bind helpers:XamlHelpers.ReverseBoolConverter(UseSameCredentialsForSending), Mode=OneWay}" />
                                 <PasswordBox
                                     x:Name="OutgoingPasswordBox"
-                                    IsEnabled="{x:Bind helpers:XamlHelpers.ReverseBoolConverter(UseSameCredentialsForSending), Mode=OneWay}"
                                     d:Header="Password"
-                                    Header="{x:Bind domain:Translator.IMAPSetupDialog_OutgoingMailServerPassword}" />
+                                    Header="{x:Bind domain:Translator.IMAPSetupDialog_OutgoingMailServerPassword}"
+                                    IsEnabled="{x:Bind helpers:XamlHelpers.ReverseBoolConverter(UseSameCredentialsForSending), Mode=OneWay}" />
                             </StackPanel>
 
                             <!--  Security and Authentication  -->
@@ -169,42 +169,42 @@
                                 </Grid.ColumnDefinitions>
                                 <!--  Security  -->
                                 <StackPanel Spacing="6">
-                                    <TextBlock Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_ConnectionSecurity}" HorizontalAlignment="Center" />
+                                    <TextBlock HorizontalAlignment="Center" Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_ConnectionSecurity}" />
                                     <ComboBox
                                         x:Name="OutgoingConnectionSecurity"
-                                        SelectedIndex="0"
                                         HorizontalAlignment="Stretch"
+                                        DisplayMemberPath="DisplayName"
                                         ItemsSource="{x:Bind AvailableConnectionSecurities}"
-                                        DisplayMemberPath="DisplayName" />
+                                        SelectedIndex="0" />
                                 </StackPanel>
 
                                 <!--  Authentication  -->
                                 <StackPanel Grid.Column="1" Spacing="6">
-                                    <TextBlock Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_AuthenticationMethod}" HorizontalAlignment="Center" />
+                                    <TextBlock HorizontalAlignment="Center" Text="{x:Bind domain:Translator.ImapAdvancedSetupDialog_AuthenticationMethod}" />
                                     <ComboBox
                                         x:Name="OutgoingAuthenticationMethod"
-                                        SelectedIndex="0"
                                         HorizontalAlignment="Stretch"
+                                        DisplayMemberPath="DisplayName"
                                         ItemsSource="{x:Bind AvailableAuthenticationMethods}"
-                                        DisplayMemberPath="DisplayName" />
+                                        SelectedIndex="0" />
                                 </StackPanel>
                             </Grid>
                         </StackPanel>
                     </muxc:TabViewItem>
-                    <muxc:TabViewItem IsClosable="False" Header="Proxy">
+                    <muxc:TabViewItem Header="Proxy" IsClosable="False">
                         <!--  Proxy  -->
-                        <StackPanel Spacing="10" Padding="12">
+                        <StackPanel Padding="12" Spacing="10">
                             <TextBlock Text="Define your optional proxy server for the connection if your mail server requires it. This is optional." />
                             <Grid ColumnSpacing="12">
                                 <Grid.ColumnDefinitions>
                                     <ColumnDefinition Width="*" />
                                     <ColumnDefinition Width="Auto" />
                                 </Grid.ColumnDefinitions>
-                                <TextBox Header="Proxy server" x:Name="ProxyServerBox" />
+                                <TextBox x:Name="ProxyServerBox" Header="Proxy server" />
                                 <muxc:NumberBox
-                                    Header="Port"
+                                    x:Name="ProxyServerPortBox"
                                     Grid.Column="1"
-                                    x:Name="ProxyServerPortBox" />
+                                    Header="Port" />
                             </Grid>
                         </StackPanel>
                     </muxc:TabViewItem>
@@ -214,10 +214,10 @@
 
         <!--  Buttons  -->
         <Grid
-            Padding="{StaticResource ImapSetupDialogSubPagePadding}"
-            Background="{ThemeResource ContentDialogBackground}"
             Grid.Row="1"
+            Padding="{StaticResource ImapSetupDialogSubPagePadding}"
             VerticalAlignment="Bottom"
+            Background="{ThemeResource ContentDialogBackground}"
             ColumnSpacing="6">
             <Grid.ColumnDefinitions>
                 <ColumnDefinition Width="*" />
@@ -225,18 +225,18 @@
             </Grid.ColumnDefinitions>
 
             <Button
-                d:Content="Cancel"
-                Content="{x:Bind domain:Translator.Buttons_Cancel}"
                 HorizontalAlignment="Stretch"
-                Click="CancelClicked" />
+                d:Content="Cancel"
+                Click="CancelClicked"
+                Content="{x:Bind domain:Translator.Buttons_Cancel}" />
 
             <Button
-                d:Content="Sign In"
-                Content="{x:Bind domain:Translator.Buttons_SignIn}"
-                Click="SignInClicked"
-                Style="{ThemeResource AccentButtonStyle}"
                 Grid.Column="1"
-                HorizontalAlignment="Stretch" />
+                HorizontalAlignment="Stretch"
+                d:Content="Sign In"
+                Click="SignInClicked"
+                Content="{x:Bind domain:Translator.Buttons_SignIn}"
+                Style="{ThemeResource AccentButtonStyle}" />
         </Grid>
     </Grid>
 </Page>

Wino.Mail/Views/ImapSetup/AdvancedImapSetupPage.xaml.cs

@@ -75,7 +75,10 @@ namespace Wino.Views.ImapSetup
         {
             base.OnNavigatedTo(e);
 
-            // ProtocolLogGrid.Visibility = Visibility.Collapsed;
+            // Don't override settings on back scenarios.
+            // User is trying to try again the same configuration.
+
+            if (e.NavigationMode == NavigationMode.Back) return;
 
             // Connection is succesfull but error occurred.
             // Imap and Smptp settings exists here at this point.

Wino.Mail/Views/ImapSetup/ImapConnectionFailedPage.xaml.cs

@@ -35,7 +35,7 @@ namespace Wino.Views.ImapSetup
 
             if (e.Parameter is ImapConnectionFailedPackage failedPackage)
             {
-                ConnectionFailedMessage.Text = failedPackage.GetErrorMessage();
+                ConnectionFailedMessage.Text = failedPackage.ErrorMessage;
 
                 ProtocolLogGrid.Visibility = !string.IsNullOrEmpty(failedPackage.ProtocolLog) ? Visibility.Visible : Visibility.Collapsed;
                 _protocolLog = failedPackage.ProtocolLog;

Wino.Mail/Views/ImapSetup/TestingImapConnectionPage.xaml

@@ -2,31 +2,102 @@
     x:Class="Wino.Views.ImapSetup.TestingImapConnectionPage"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:local="using:Wino.Views.ImapSetup"
+    xmlns:controls="using:Wino.Controls"
-    xmlns:muxc="using:Microsoft.UI.Xaml.Controls"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
-    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:domain="using:Wino.Core.Domain"
+    xmlns:local="using:Wino.Views.ImapSetup"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:muxc="using:Microsoft.UI.Xaml.Controls"
     mc:Ignorable="d">
 
     <Grid>
         <!--  Testing Connection Panel  -->
         <StackPanel
             x:Name="TestingConnectionPanel"
-            VerticalAlignment="Center"
+            HorizontalAlignment="Center"
-            HorizontalAlignment="Center">
+            VerticalAlignment="Center">
 
             <Viewbox
-                VerticalAlignment="Center"
-                HorizontalAlignment="Center"
                 Width="26"
-                Height="26">
+                Height="26"
+                HorizontalAlignment="Center"
+                VerticalAlignment="Center">
                 <PathIcon Data="F1 M 18.75 18.125 C 18.75 18.294271 18.68815 18.440756 18.564453 18.564453 C 18.440754 18.68815 18.29427 18.75 18.125 18.75 L 13.75 18.75 C 13.75 18.925781 13.717447 19.088541 13.652344 19.238281 C 13.587239 19.388021 13.497721 19.519857 13.383789 19.633789 C 13.269855 19.747721 13.13802 19.83724 12.988281 19.902344 C 12.838541 19.967447 12.675781 20 12.5 20 L 6.25 20 C 6.074219 20 5.909831 19.967447 5.756836 19.902344 C 5.603841 19.83724 5.472005 19.74935 5.361328 19.638672 C 5.250651 19.527994 5.16276 19.396158 5.097656 19.243164 C 5.032552 19.09017 5 18.925781 5 18.75 L 0.625 18.75 C 0.455729 18.75 0.309245 18.68815 0.185547 18.564453 C 0.061849 18.440756 0 18.294271 0 18.125 C 0 17.955729 0.061849 17.809244 0.185547 17.685547 C 0.309245 17.56185 0.455729 17.5 0.625 17.5 L 5 17.5 C 5 17.154949 5.120442 16.86198 5.361328 16.621094 C 5.608724 16.373699 5.904948 16.25 6.25 16.25 L 7.5 16.25 C 7.5 16.074219 7.532552 15.911459 7.597656 15.761719 C 7.66276 15.611979 7.752278 15.480144 7.866211 15.366211 C 7.980143 15.252279 8.111979 15.162761 8.261719 15.097656 C 8.411458 15.032553 8.574219 15 8.75 15 L 8.75 13.75 L 6.875 13.75 C 6.621094 13.75 6.380208 13.701172 6.152344 13.603516 C 5.924479 13.505859 5.724284 13.370769 5.551758 13.198242 C 5.379231 13.025717 5.244141 12.825521 5.146484 12.597656 C 5.048828 12.369792 5 12.128906 5 11.875 L 5 1.875 C 5 1.621094 5.048828 1.380209 5.146484 1.152344 C 5.244141 0.92448 5.379231 0.724285 5.551758 0.551758 C 5.724284 0.379232 5.924479 0.244141 6.152344 0.146484 C 6.380208 0.048828 6.621094 0 6.875 0 L 11.875 0 C 12.128906 0 12.369791 0.048828 12.597656 0.146484 C 12.825521 0.244141 13.025716 0.379232 13.198242 0.551758 C 13.370768 0.724285 13.505859 0.92448 13.603516 1.152344 C 13.701172 1.380209 13.75 1.621094 13.75 1.875 L 13.75 11.875 C 13.75 12.128906 13.701172 12.369792 13.603516 12.597656 C 13.505859 12.825521 13.370768 13.025717 13.198242 13.198242 C 13.025716 13.370769 12.825521 13.505859 12.597656 13.603516 C 12.369791 13.701172 12.128906 13.75 11.875 13.75 L 10 13.75 L 10 15 C 10.169271 15 10.330403 15.032553 10.483398 15.097656 C 10.636393 15.162761 10.769856 15.252279 10.883789 15.366211 C 10.997721 15.480144 11.087239 15.613607 11.152344 15.766602 C 11.217447 15.919597 11.25 16.080729 11.25 16.25 L 12.5 16.25 C 12.669271 16.25 12.828775 16.282553 12.978516 16.347656 C 13.128255 16.41276 13.261719 16.503906 13.378906 16.621094 C 13.626302 16.86849 13.75 17.161459 13.75 17.5 L 18.125 17.5 C 18.29427 17.5 18.440754 17.56185 18.564453 17.685547 C 18.68815 17.809244 18.75 17.955729 18.75 18.125 Z M 11.875 12.5 C 12.04427 12.5 12.190754 12.438151 12.314453 12.314453 C 12.43815 12.190756 12.5 12.044271 12.5 11.875 L 12.5 1.875 C 12.5 1.70573 12.43815 1.559246 12.314453 1.435547 C 12.190754 1.31185 12.04427 1.25 11.875 1.25 L 6.875 1.25 C 6.705729 1.25 6.559244 1.31185 6.435547 1.435547 C 6.311849 1.559246 6.25 1.70573 6.25 1.875 L 6.25 11.875 C 6.25 12.044271 6.311849 12.190756 6.435547 12.314453 C 6.559244 12.438151 6.705729 12.5 6.875 12.5 Z M 10.625 2.5 C 10.794271 2.5 10.940755 2.56185 11.064453 2.685547 C 11.18815 2.809246 11.25 2.95573 11.25 3.125 C 11.25 3.294271 11.18815 3.440756 11.064453 3.564453 C 10.940755 3.688152 10.794271 3.75 10.625 3.75 L 8.125 3.75 C 7.955729 3.75 7.809245 3.688152 7.685547 3.564453 C 7.561849 3.440756 7.5 3.294271 7.5 3.125 C 7.5 2.95573 7.561849 2.809246 7.685547 2.685547 C 7.809245 2.56185 7.955729 2.5 8.125 2.5 Z M 10.625 5 C 10.794271 5.000001 10.940755 5.06185 11.064453 5.185547 C 11.18815 5.309245 11.25 5.455729 11.25 5.625 C 11.25 5.794271 11.18815 5.940756 11.064453 6.064453 C 10.940755 6.188151 10.794271 6.25 10.625 6.25 L 8.125 6.25 C 7.955729 6.25 7.809245 6.188151 7.685547 6.064453 C 7.561849 5.940756 7.5 5.794271 7.5 5.625 C 7.5 5.455729 7.561849 5.309245 7.685547 5.185547 C 7.809245 5.06185 7.955729 5.000001 8.125 5 Z M 12.5 18.75 L 12.5 17.5 L 10.625 17.5 C 10.481771 17.5 10.367838 17.47233 10.283203 17.416992 C 10.198567 17.361654 10.135091 17.290039 10.092773 17.202148 C 10.050455 17.114258 10.022786 17.016602 10.009766 16.90918 C 9.996744 16.801758 9.990234 16.692709 9.990234 16.582031 C 9.990234 16.523438 9.991861 16.466471 9.995117 16.411133 C 9.998372 16.355795 10 16.302084 10 16.25 L 8.75 16.25 L 8.75 16.582031 C 8.75 16.692709 8.743489 16.801758 8.730469 16.90918 C 8.717447 17.016602 8.689778 17.114258 8.647461 17.202148 C 8.605143 17.290039 8.543294 17.361654 8.461914 17.416992 C 8.380533 17.47233 8.268229 17.5 8.125 17.5 L 6.25 17.5 L 6.25 18.75 Z " />
             </Viewbox>
 
             <TextBlock Text="{x:Bind domain:Translator.TestingImapConnectionMessage}" />
 
-            <muxc:ProgressBar IsIndeterminate="True" Margin="0,4,0,0" />
+            <muxc:ProgressBar Margin="0,4,0,0" IsIndeterminate="True" />
         </StackPanel>
+
+        <!--  Allow untrusted certificate dialog  -->
+        <Grid
+            x:Name="CertificateDialog"
+            MaxWidth="600"
+            Padding="20"
+            RowSpacing="12"
+            Visibility="Collapsed">
+            <Grid.RowDefinitions>
+                <RowDefinition Height="Auto" />
+                <RowDefinition Height="Auto" />
+                <RowDefinition Height="Auto" />
+                <RowDefinition Height="*" />
+            </Grid.RowDefinitions>
+
+            <controls:WinoFontIcon FontSize="46" Icon="Certificate" />
+
+            <TextBlock
+                Grid.Row="1"
+                Margin="0,16,0,6"
+                TextWrapping="WrapWholeWords">
+                <Run Text="{x:Bind domain:Translator.IMAPSetupDialog_CertificateAllowanceRequired_Row0}" />
+                <LineBreak />
+                <Run Text="{x:Bind domain:Translator.IMAPSetupDialog_CertificateAllowanceRequired_Row1}" />
+            </TextBlock>
+
+            <!--  Cert details  -->
+            <StackPanel Grid.Row="2" Spacing="6">
+                <TextBlock TextWrapping="Wrap">
+                    <Run FontWeight="SemiBold" Text="{x:Bind domain:Translator.IMAPSetupDialog_CertificateIssuer}" />
+                    <LineBreak />
+                    <Run x:Name="CertIssuer" />
+                </TextBlock>
+
+                <TextBlock>
+                    <Run FontWeight="SemiBold" Text="{x:Bind domain:Translator.IMAPSetupDialog_CertificateValidFrom}" />
+                    <LineBreak />
+                    <Run x:Name="CertValidFrom" />
+                </TextBlock>
+
+                <TextBlock>
+                    <Run FontWeight="SemiBold" Text="{x:Bind domain:Translator.IMAPSetupDialog_CertificateValidTo}" />
+                    <LineBreak />
+                    <Run x:Name="CertValidTo" />
+                </TextBlock>
+            </StackPanel>
+
+            <Grid
+                Grid.Row="3"
+                Margin="0,16"
+                ColumnSpacing="12">
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="*" />
+                    <ColumnDefinition Width="*" />
+                </Grid.ColumnDefinitions>
+                <Button
+                    x:Name="DenyCertificateButton"
+                    HorizontalAlignment="Stretch"
+                    Click="DenyClicked"
+                    Content="{x:Bind domain:Translator.Buttons_Deny}" />
+
+                <Button
+                    x:Name="AllowCertificateButton"
+                    Grid.Column="1"
+                    HorizontalAlignment="Stretch"
+                    Click="AllowClicked"
+                    Content="{x:Bind domain:Translator.Buttons_Allow}"
+                    Style="{StaticResource AccentButtonStyle}" />
+            </Grid>
+        </Grid>
     </Grid>
 </Page>

Wino.Mail/Views/ImapSetup/TestingImapConnectionPage.xaml.cs

@@ -4,35 +4,29 @@ using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.Extensions.DependencyInjection;
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Navigation;
+using Wino.Core.Domain;
 using Wino.Core.Domain.Entities;
 using Wino.Core.Domain.Exceptions;
 using Wino.Core.Domain.Interfaces;
 using Wino.Core.Domain.Models.AutoDiscovery;
+using Wino.Core.Domain.Models.Connectivity;
 using Wino.Messaging.Client.Mails;
+using Wino.Messaging.Server;
 
 
 namespace Wino.Views.ImapSetup
 {
     public sealed partial class TestingImapConnectionPage : Page
     {
-        private IImapTestService _imapTestService = App.Current.Services.GetService<IImapTestService>();
+        private IWinoServerConnectionManager _winoServerConnectionManager = App.Current.Services.GetService<IWinoServerConnectionManager>();
+        private AutoDiscoverySettings autoDiscoverySettings;
+        private CustomServerInformation serverInformationToTest;
 
         public TestingImapConnectionPage()
         {
             InitializeComponent();
         }
 
-        private async Task TryTestConnectionAsync(CustomServerInformation serverInformation)
-        {
-            await Task.Delay(1000);
-
-            await _imapTestService.TestImapConnectionAsync(serverInformation);
-
-            // All success. Finish setup with validated server information.
-
-            WeakReferenceMessenger.Default.Send(new ImapSetupDismissRequested(serverInformation));
-        }
-
         protected override async void OnNavigatedTo(NavigationEventArgs e)
         {
             base.OnNavigatedTo(e);
@@ -47,9 +41,6 @@ namespace Wino.Views.ImapSetup
             {
                 // Test connection
 
-                CustomServerInformation serverInformationToTest = null;
-                AutoDiscoverySettings autoDiscoverySettings = null;
-
                 // Discovery settings are passed.
                 // Create server information out of the discovery settings.
                 if (e.Parameter is AutoDiscoverySettings parameterAutoDiscoverySettings)
@@ -63,19 +54,80 @@ namespace Wino.Views.ImapSetup
                     serverInformationToTest = customServerInformation;
                 }
 
-                try
+                // Make sure that certificate dialog must be present in case of SSL handshake fails.
-                {
+                await PerformTestAsync(allowSSLHandshake: false);
-                    await TryTestConnectionAsync(serverInformationToTest);
             }
-                catch (Exception ex)
+        }
+
+        private async Task PerformTestAsync(bool allowSSLHandshake)
         {
-                    string protocolLog = ex is ImapClientPoolException clientPoolException ? clientPoolException.ProtocolLog : string.Empty;
+            CertificateDialog.Visibility = Windows.UI.Xaml.Visibility.Collapsed;
+            TestingConnectionPanel.Visibility = Windows.UI.Xaml.Visibility.Visible;
 
-                    var failurePackage = new ImapConnectionFailedPackage(ex, protocolLog, autoDiscoverySettings);
+            await Task.Delay(1000);
 
+            var testResultResponse = await _winoServerConnectionManager
+                .GetResponseAsync<ImapConnectivityTestResults, ImapConnectivityTestRequested>(new ImapConnectivityTestRequested(serverInformationToTest, allowSSLHandshake));
+
+            if (!testResultResponse.IsSuccess)
+            {
+                // Wino Server is connection is failed.
+                ReturnWithError(testResultResponse.Message);
+            }
+            else
+            {
+                var testResultData = testResultResponse.Data;
+
+                if (testResultData.IsSuccess)
+                {
+                    // All success. Finish setup with validated server information.
+                    ReturnWithSuccess();
+                }
+                else
+                {
+                    // Check if certificate UI is required.
+
+                    if (testResultData.IsCertificateUIRequired)
+                    {
+                        // Certificate UI is required. Show certificate dialog.
+
+                        CertIssuer.Text = testResultData.CertificateIssuer;
+                        CertValidFrom.Text = testResultData.CertificateValidFromDateString;
+                        CertValidTo.Text = testResultData.CertificateExpirationDateString;
+
+                        TestingConnectionPanel.Visibility = Windows.UI.Xaml.Visibility.Collapsed;
+                        CertificateDialog.Visibility = Windows.UI.Xaml.Visibility.Visible;
+                    }
+                    else
+                    {
+                        // Connection test failed. Show error dialog.
+
+                        var protocolLog = testResultData.FailureProtocolLog;
+
+                        ReturnWithError(testResultData.FailedReason, protocolLog);
+                    }
+                }
+            }
+        }
+
+        private void ReturnWithError(string error, string protocolLog = "")
+        {
+            var failurePackage = new ImapConnectionFailedPackage(error, protocolLog, autoDiscoverySettings);
             WeakReferenceMessenger.Default.Send(new ImapSetupBackNavigationRequested(typeof(ImapConnectionFailedPage), failurePackage));
         }
-            }
+
+        private void ReturnWithSuccess()
+            => WeakReferenceMessenger.Default.Send(new ImapSetupDismissRequested(serverInformationToTest));
+
+        private void DenyClicked(object sender, Windows.UI.Xaml.RoutedEventArgs e)
+            => ReturnWithError(Translator.IMAPSetupDialog_CertificateDenied, string.Empty);
+
+        private async void AllowClicked(object sender, Windows.UI.Xaml.RoutedEventArgs e)
+        {
+            // Run the test again, but this time allow SSL handshake.
+            // Any authentication error will be shown to the user after this test.
+
+            await PerformTestAsync(allowSSLHandshake: true);
         }
     }
 }

Wino.Mail/Views/ImapSetup/WelcomeImapSetupPage.xaml.cs

@@ -59,7 +59,7 @@ namespace Wino.Views.ImapSetup
             {
                 // Couldn't find settings.
 
-                var failurePackage = new ImapConnectionFailedPackage(new Exception(Translator.Exception_ImapAutoDiscoveryFailed), string.Empty, discoverySettings);
+                var failurePackage = new ImapConnectionFailedPackage(Translator.Exception_ImapAutoDiscoveryFailed, string.Empty, discoverySettings);
 
                 WeakReferenceMessenger.Default.Send(new ImapSetupBackNavigationRequested(typeof(ImapConnectionFailedPage), failurePackage));
             }

Wino.Mail/Views/MailListPage.xaml

@@ -291,6 +291,7 @@
                         Unchecked="SelectAllCheckboxUnchecked"
                         Visibility="{x:Bind helpers:XamlHelpers.IsSelectionModeMultiple(MailListView.SelectionMode), Mode=OneWay}" />
 
+                    
                     <!--  Folders  -->
                     <toolkit:Segmented
                         Grid.Row="1"

Wino.Messages/Server/ImapConnectivityTestRequested.cs

@@ -0,0 +1,7 @@
+using Wino.Core.Domain.Entities;
+using Wino.Core.Domain.Interfaces;
+
+namespace Wino.Messaging.Server
+{
+    public record ImapConnectivityTestRequested(CustomServerInformation ServerInformation, bool IsSSLHandshakeAllowed) : IClientMessage;
+}

Wino.Messages/UI/CopyAuthURLRequested.cs

@@ -1,6 +1,4 @@
-using Wino.Messaging.UI;
+namespace Wino.Messaging.UI
-
-namespace Wino.Messaging.Server
 {
     /// <summary>
     /// When authenticators are proposed to copy the auth URL on the UI.

Wino.Server/Core/ServerMessageHandlerFactory.cs

@@ -22,6 +22,7 @@ namespace Wino.Server.Core
                 nameof(SynchronizationExistenceCheckRequest) => App.Current.Services.GetService<SyncExistenceHandler>(),
                 nameof(ServerTerminationModeChanged) => App.Current.Services.GetService<ServerTerminationModeHandler>(),
                 nameof(TerminateServerRequested) => App.Current.Services.GetService<TerminateServerRequestHandler>(),
+                nameof(ImapConnectivityTestRequested) => App.Current.Services.GetService<ImapConnectivityTestHandler>(),
                 _ => throw new Exception($"Server handler for {typeName} is not registered."),
             };
         }
@@ -38,6 +39,7 @@ namespace Wino.Server.Core
             serviceCollection.AddTransient<SyncExistenceHandler>();
             serviceCollection.AddTransient<ServerTerminationModeHandler>();
             serviceCollection.AddTransient<TerminateServerRequestHandler>();
+            serviceCollection.AddTransient<ImapConnectivityTestHandler>();
         }
     }
 }

Wino.Server/MessageHandlers/ImapConnectivityTestHandler.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Wino.Core.Domain.Exceptions;
+using Wino.Core.Domain.Interfaces;
+using Wino.Core.Domain.Models.Connectivity;
+using Wino.Core.Domain.Models.Server;
+using Wino.Messaging.Server;
+using Wino.Server.Core;
+
+namespace Wino.Server.MessageHandlers
+{
+    public class ImapConnectivityTestHandler : ServerMessageHandler<ImapConnectivityTestRequested, ImapConnectivityTestResults>
+    {
+        private readonly IImapTestService _imapTestService;
+
+        public override WinoServerResponse<ImapConnectivityTestResults> FailureDefaultResponse(Exception ex)
+            => WinoServerResponse<ImapConnectivityTestResults>.CreateErrorResponse(ex.Message);
+
+        public ImapConnectivityTestHandler(IImapTestService imapTestService)
+        {
+            _imapTestService = imapTestService;
+        }
+
+        protected override async Task<WinoServerResponse<ImapConnectivityTestResults>> HandleAsync(ImapConnectivityTestRequested message, CancellationToken cancellationToken = default)
+        {
+            try
+            {
+                await _imapTestService.TestImapConnectionAsync(message.ServerInformation, message.IsSSLHandshakeAllowed);
+
+                return WinoServerResponse<ImapConnectivityTestResults>.CreateSuccessResponse(ImapConnectivityTestResults.Success());
+            }
+            catch (ImapTestSSLCertificateException sslTestException)
+            {
+                // User must confirm to continue ignoring the SSL certificate.
+                return WinoServerResponse<ImapConnectivityTestResults>.CreateSuccessResponse(ImapConnectivityTestResults.CertificateUIRequired(sslTestException.Issuer, sslTestException.ExpirationDateString, sslTestException.ValidFromDateString));
+            }
+            catch (ImapClientPoolException clientPoolException)
+            {
+                // Connectivity failed with protocol log.
+                return WinoServerResponse<ImapConnectivityTestResults>.CreateSuccessResponse(ImapConnectivityTestResults.Failure(clientPoolException, clientPoolException.ProtocolLog));
+            }
+            catch (Exception exception)
+            {
+                // Unknown error 
+                return WinoServerResponse<ImapConnectivityTestResults>.CreateSuccessResponse(ImapConnectivityTestResults.Failure(exception, string.Empty));
+            }
+        }
+    }
+}

Wino.Server/ServerContext.cs

@@ -315,7 +315,9 @@ namespace Wino.Server
                 case nameof(ServerTerminationModeChanged):
                     await ExecuteServerMessageSafeAsync(args, JsonSerializer.Deserialize<ServerTerminationModeChanged>(messageJson, _jsonSerializerOptions));
                     break;
-
+                case nameof(ImapConnectivityTestRequested):
+                    await ExecuteServerMessageSafeAsync(args, JsonSerializer.Deserialize<ImapConnectivityTestRequested>(messageJson, _jsonSerializerOptions));
+                    break;
                 case nameof(TerminateServerRequested):
                     await ExecuteServerMessageSafeAsync(args, JsonSerializer.Deserialize<TerminateServerRequested>(messageJson, _jsonSerializerOptions));