improvement: Headers in SendEmail don't overwrite default headers any…

…more; added ReplyTo

docs/Email/README.md

@@ -47,5 +47,5 @@ container.Collections.Append<IEmailAttachmentResolver, YourResolver>()
 
 ## Headers
 
-No special Headers are sent per default, however with the `Headers` overload on `SendEmail`, `MimeKit.Header`s can be added to the email (overrides all Headers defined in `EmailOptions.DefaultHeaders`). With `EmailOptions.DefaultHeaders` default headers can be set for all emails. Predefined sets of headers can be found in `EmailHeaders`:
-- `DiscourageAutoReplies` includes [`Precedence:list`](https://www.rfc-editor.org/rfc/rfc3834), [`AutoSubmitted:generated`](https://www.rfc-editor.org/rfc/rfc3834), and [`X-Auto-Response-Suppress:All`](https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxcmail/e489ffaf-19ed-4285-96d9-c31c42cab17f). They discourage email servers to sent auto replies.
+No special Headers are sent per default, however with the `Headers` parameter on `SendEmail`, `MimeKit.Header`s can be added to the email (overrides all Headers defined in `EmailOptions.DefaultHeaders`). With `EmailOptions.DefaultHeaders` default headers can be set for all emails. Predefined sets of headers can be found in `EmailHeaders`:
+- `DiscourageAutoReplies` includes [`Precedence:list`](https://www.rfc-editor.org/rfc/rfc3834#section-3.1.8), [`AutoSubmitted:generated`](https://www.rfc-editor.org/rfc/rfc3834#section-3.1.7), and [`X-Auto-Response-Suppress:All`](https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxcmail/e489ffaf-19ed-4285-96d9-c31c42cab17f). They discourage email servers to sent auto replies.

src/Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <Version>7.3.0</Version>
+    <Version>7.4.0</Version>
     <TargetFramework>net7.0</TargetFramework>
   </PropertyGroup>
 

src/Email/src/EmailHeaders.cs

@@ -9,9 +9,9 @@ public static class EmailHeaders
 {
     public static readonly IReadOnlyDictionary<string, string> DiscourageAutoReplies = new Dictionary<string, string>
     {
-        // https://www.rfc-editor.org/rfc/rfc3834 RFC3834 Section 2 §1
+        // https://www.rfc-editor.org/rfc/rfc3834#section-3.1.8 RFC3834 Section 3.1.8
         [HeaderId.Precedence.ToHeaderName()] = "list",
-        // https://www.rfc-editor.org/rfc/rfc3834 RFC3834 Section 2 §8
+        // https://www.rfc-editor.org/rfc/rfc3834#section-3.1.7 RFC3834 Section 3.1.7
         [HeaderId.AutoSubmitted.ToHeaderName()] = "generated",
         // https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxcmail/e489ffaf-19ed-4285-96d9-c31c42cab17f MS-OXCMAIL Section 2.2.3.2.14
         ["X-Auto-Response-Suppress"] = "All"

src/Email/src/SendEmail.cs

@@ -11,15 +11,16 @@ namespace Fusonic.Extensions.Email;
 /// <summary>
 /// Sends an email in the background.
 /// </summary>
-/// <param name="Recipient">Email-address of the recipient</param>
-/// <param name="RecipientDisplayName">Display name of the recipient</param>
-/// <param name="Culture">Culture to render the email in</param>
+/// <param name="Recipient">Email-address of the recipient.</param>
+/// <param name="RecipientDisplayName">Display name of the recipient.</param>
+/// <param name="Culture">Culture to render the email in.</param>
 /// <param name="ViewModel">View model for the email. The model must have an [EmailView]-attribute, providing the path to the email to render (cshtml).</param>
 /// <param name="SubjectKey">Subject key to get the subject of the email from the ViewLocalizer. If null, the SubjectKey from the EmailViewAttribute will be used.</param>
 /// <param name="BccRecipient">Email-address of the BCC recipient. Optional.</param>
 /// <param name="Attachments">Attachments for the email.</param>
 /// <param name="SubjectFormatParameters">String formatting parameters for the translated subject. <code>subject = string.Format(subject, SubjectFormatParameters)</code></param>
-/// <param name="Headers">Adds the specified Headers to the email and overrides all default headers from the <seealso cref="EmailOptions.DefaultHeaders"/>.</param>
+/// <param name="Headers">Adds the specified headers to the email and overrides the default headers from the <seealso cref="EmailOptions.DefaultHeaders"/>.</param>
+/// <param name="ReplyTo">Sets the value as the Reply-To header in the email.</param>
 public record SendEmail(
     string Recipient,
     string RecipientDisplayName,
@@ -29,7 +30,8 @@ public record SendEmail(
     string? BccRecipient = null,
     Attachment[]? Attachments = null,
     object[]? SubjectFormatParameters = null,
-    IReadOnlyDictionary<string, string>? Headers = null) : ICommand
+    IReadOnlyDictionary<string, string>? Headers = null,
+    string? ReplyTo = null) : ICommand
 {
     [OutOfBand]
     public class Handler : AsyncRequestHandler<SendEmail>, IAsyncDisposable
@@ -63,21 +65,19 @@ protected override async Task Handle(SendEmail request, CancellationToken cancel
                 Subject = subject
             };
 
-            var headers = request.Headers ?? emailOptions.DefaultHeaders;
-
-            if (headers != null)
+            if (!string.IsNullOrWhiteSpace(request.BccRecipient))
             {
-                foreach (var (field, value) in headers)
-                {
-                    message.Headers.Add(field, value);
-                }
+                message.Bcc.Add(new MailboxAddress(request.BccRecipient, request.BccRecipient));
             }
 
-            if (!string.IsNullOrWhiteSpace(request.BccRecipient))
+            if (!string.IsNullOrWhiteSpace(request.ReplyTo))
             {
-                message.Bcc.Add(new MailboxAddress(request.BccRecipient, request.BccRecipient));
+                message.ReplyTo.Add(new MailboxAddress(string.Empty, request.ReplyTo));
             }
 
+            SetHeaders(emailOptions.DefaultHeaders);
+            SetHeaders(request.Headers);
+
             try
             {
                 await smtpClient.SendMailAsync(message);
@@ -86,6 +86,17 @@ protected override async Task Handle(SendEmail request, CancellationToken cancel
             {
                 await DisposeStreams();
             }
+
+            void SetHeaders(IReadOnlyDictionary<string, string>? headers)
+            {
+                if (headers == null)
+                    return;
+
+                foreach (var (field, value) in headers)
+                {
+                    message.Headers[field] = value;
+                }
+            }
         }
 
         private async Task<MimeEntity> GetMessageBody(string htmlBody, Attachment[]? attachments, CancellationToken cancellationToken)

src/Email/test/SendEmailTests.cs

@@ -148,25 +148,40 @@ public async Task SendEmail_DefaultHeadersAdded()
     }
 
     [Fact]
-    public async Task SendEmail_DefaultHeadersOverridden()
+    public async Task SendEmail_DefaultHeadersOverriddenIfSetTwice()
     {
         Fixture.SmtpServer!.ClearReceivedEmail();
 
         var options = GetInstance<EmailOptions>();
 
-        options.DefaultHeaders = new Dictionary<string, string> { ["my-header"] = "value" };
+        options.DefaultHeaders = new Dictionary<string, string> { ["replaced"] = "value", ["default"] = "value" };
 
         var model = new SendEmailTestEmailViewModel { SomeField = "Some field." };
-        await SendAsync(new SendEmail("[email protected]", "The Recipient", new CultureInfo("de-AT"), model, Headers: new Dictionary<string, string> { ["new-header"] = "new-value" }));
+        await SendAsync(new SendEmail("[email protected]", "The Recipient", new CultureInfo("de-AT"), model, Headers: new Dictionary<string, string> { ["replaced"] = "new-value" }));
 
         Fixture.SmtpServer.ReceivedEmailCount.Should().Be(1);
         var email = Fixture.SmtpServer.ReceivedEmail.Single();
 
-        email.Headers.AllKeys.Should().NotContain("my-header");
-        email.Headers.AllKeys.Should().Contain("new-header");
-        email.Headers["new-header"].Should().Be("new-value");
+        email.Headers.AllKeys.Should().Contain("replaced");
+        email.Headers["replaced"].Should().Be("new-value");
+        email.Headers.AllKeys.Should().Contain("default");
+        email.Headers["default"].Should().Be("value");
     }
 
+    [Fact]
+    public async Task SendEmail_ReplyToAdded()
+    {
+        Fixture.SmtpServer!.ClearReceivedEmail();
+
+        var model = new SendEmailTestEmailViewModel { SomeField = "Some field." };
+        await SendAsync(new SendEmail("[email protected]", "The Recipient", new CultureInfo("de-AT"), model, ReplyTo: "[email protected]"));
+
+        Fixture.SmtpServer.ReceivedEmailCount.Should().Be(1);
+        var email = Fixture.SmtpServer.ReceivedEmail.Single();
+
+        email.Headers.AllKeys.Should().Contain("Reply-To");
+        email.Headers["Reply-To"].Should().Be("[email protected]");
+    }
 
     [Fact]
     public async Task SendEmail_InvalidBccEmailAddress_ThrowsException()