Threading improvements.

Wino.Core.Domain/Extensions/MailHeaderExtensions.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Linq;
+
+namespace Wino.Core.Domain.Extensions;
+
+public static class MailHeaderExtensions
+{
+    /// <summary>
+    /// Strips angle brackets from a Message-ID or In-Reply-To value.
+    /// RFC 5322 Message-IDs are formatted as &lt;id@domain&gt;, but MimeKit
+    /// properties store them without brackets. This normalizes raw header
+    /// values to match MimeKit's convention.
+    /// </summary>
+    public static string StripAngleBrackets(string value)
+    {
+        if (string.IsNullOrEmpty(value)) return value;
+
+        value = value.Trim();
+
+        if (value.StartsWith("<") && value.EndsWith(">"))
+            return value.Substring(1, value.Length - 2);
+
+        return value;
+    }
+
+    /// <summary>
+    /// Normalizes a raw RFC References header value into semicolon-separated Message-IDs
+    /// without angle brackets. Raw References headers contain space-separated bracketed IDs
+    /// like "&lt;id1@domain&gt; &lt;id2@domain&gt;". This converts them to "id1@domain;id2@domain".
+    /// </summary>
+    public static string NormalizeReferences(string rawReferences)
+    {
+        if (string.IsNullOrEmpty(rawReferences)) return rawReferences;
+
+        var ids = rawReferences
+            .Split(new[] { ' ', '\t', '\r', '\n', ';', ',' }, StringSplitOptions.RemoveEmptyEntries)
+            .Select(StripAngleBrackets)
+            .Where(id => !string.IsNullOrEmpty(id));
+
+        return string.Join(";", ids);
+    }
+}