Add read receipt tracking for sent mail

2026-04-11 21:02:51 +02:00
parent d5c121ce24
commit 230039cb57
29 changed files with 690 additions and 21 deletions
@@ -0,0 +1,111 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using MimeKit;
+
+namespace Wino.Core.Domain.Extensions;
+
+public static class ReadReceiptExtensions
+{
+    public static bool HasReadReceiptRequest(this MimeMessage mimeMessage)
+        => mimeMessage?.Headers?.Contains(Constants.DispositionNotificationToHeader) == true
+           && !string.IsNullOrWhiteSpace(mimeMessage.Headers[Constants.DispositionNotificationToHeader]);
+
+    public static void SetReadReceiptRequest(this MimeMessage mimeMessage, string address, bool isRequested)
+    {
+        if (mimeMessage == null)
+            return;
+
+        mimeMessage.Headers.Remove(Constants.DispositionNotificationToHeader);
+
+        if (isRequested && !string.IsNullOrWhiteSpace(address))
+        {
+            mimeMessage.Headers.Add(Constants.DispositionNotificationToHeader, address.Trim());
+        }
+    }
+
+    public static bool LooksLikeReadReceipt(this MimeMessage mimeMessage)
+    {
+        if (mimeMessage?.Body == null)
+            return false;
+
+        return mimeMessage.BodyParts.Any(IsReadReceiptEntity) || IsReadReceiptEntity(mimeMessage.Body);
+    }
+
+    public static ReadReceiptParseResult ParseReadReceipt(this MimeMessage mimeMessage)
+    {
+        if (!mimeMessage.LooksLikeReadReceipt())
+            return ReadReceiptParseResult.Empty;
+
+        var entity = mimeMessage.BodyParts.FirstOrDefault(IsReadReceiptEntity) ?? mimeMessage.Body;
+        var lines = ReadEntityLines(entity);
+
+        string originalMessageId = null;
+
+        foreach (var line in lines)
+        {
+            if (line.StartsWith(Constants.OriginalMessageIdHeader + ":", StringComparison.OrdinalIgnoreCase))
+            {
+                originalMessageId = line.Substring(line.IndexOf(':') + 1).Trim();
+                break;
+            }
+        }
+
+        var acknowledgedAtUtc = mimeMessage.Date != DateTimeOffset.MinValue
+            ? mimeMessage.Date.UtcDateTime
+            : (DateTime?)null;
+
+        return new ReadReceiptParseResult(
+            true,
+            MailHeaderExtensions.NormalizeMessageId(originalMessageId),
+            acknowledgedAtUtc);
+    }
+
+    private static bool IsReadReceiptEntity(MimeEntity entity)
+    {
+        if (entity?.ContentType == null)
+            return false;
+
+        if (entity.ContentType.MimeType.Equals("message/disposition-notification", StringComparison.OrdinalIgnoreCase))
+            return true;
+
+        var reportType = entity.ContentType.Parameters["report-type"];
+        return entity.ContentType.MimeType.Equals("multipart/report", StringComparison.OrdinalIgnoreCase)
+               && !string.IsNullOrWhiteSpace(reportType)
+               && reportType.Equals("disposition-notification", StringComparison.OrdinalIgnoreCase);
+    }
+
+    private static IEnumerable<string> ReadEntityLines(MimeEntity entity)
+    {
+        if (entity is TextPart textPart)
+        {
+            return SplitLines(textPart.Text);
+        }
+
+        if (entity is MimePart mimePart)
+        {
+            using var memoryStream = new MemoryStream();
+            mimePart.Content?.DecodeTo(memoryStream);
+            memoryStream.Position = 0;
+            using var reader = new StreamReader(memoryStream);
+            return SplitLines(reader.ReadToEnd());
+        }
+
+        using var serializedStream = new MemoryStream();
+        entity.WriteTo(serializedStream);
+        serializedStream.Position = 0;
+        using var serializedReader = new StreamReader(serializedStream);
+        return SplitLines(serializedReader.ReadToEnd());
+    }
+
+    private static IEnumerable<string> SplitLines(string content)
+        => string.IsNullOrWhiteSpace(content)
+            ? []
+            : content.Split(["\r\n", "\n"], StringSplitOptions.RemoveEmptyEntries);
+}
+
+public sealed record ReadReceiptParseResult(bool IsReadReceipt, string OriginalMessageId, DateTime? AcknowledgedAtUtc)
+{
+    public static ReadReceiptParseResult Empty { get; } = new(false, string.Empty, null);
+}