From 0fda72c6b04e9627b4a42da1f8de1acbc6b3f6ad Mon Sep 17 00:00:00 2001
From: Kyle Spearrin <kyle.spearrin@gmail.com>
Date: Mon, 10 Sep 2018 08:45:57 -0400
Subject: [PATCH] add message id header to smtp mail

---
 .../Services/Implementations/SmtpMailDeliveryService.cs  | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/Core/Services/Implementations/SmtpMailDeliveryService.cs b/src/Core/Services/Implementations/SmtpMailDeliveryService.cs
index 6b7b80f472..5f206686e8 100644
--- a/src/Core/Services/Implementations/SmtpMailDeliveryService.cs
+++ b/src/Core/Services/Implementations/SmtpMailDeliveryService.cs
@@ -11,6 +11,7 @@ namespace Bit.Core.Services
     {
         private readonly GlobalSettings _globalSettings;
         private readonly ILogger<SmtpMailDeliveryService> _logger;
+        private readonly string _replyDomain;
 
         public SmtpMailDeliveryService(
             GlobalSettings globalSettings,
@@ -20,6 +21,10 @@ namespace Bit.Core.Services
             {
                 throw new ArgumentNullException(nameof(globalSettings.Mail.Smtp.Host));
             }
+            if(globalSettings.Mail?.ReplyToEmail?.Contains("@") ?? false)
+            {
+                _replyDomain = globalSettings.Mail.ReplyToEmail.Split('@')[1];
+            }
 
             _globalSettings = globalSettings;
             _logger = logger;
@@ -57,6 +62,10 @@ namespace Bit.Core.Services
             smtpMessage.SubjectEncoding = Encoding.UTF8;
             smtpMessage.BodyEncoding = Encoding.UTF8;
             smtpMessage.BodyTransferEncoding = System.Net.Mime.TransferEncoding.QuotedPrintable;
+            if(!string.IsNullOrWhiteSpace(_replyDomain))
+            {
+                smtpMessage.Headers.Add("Message-ID", $"<{Guid.NewGuid()}@{_replyDomain}>");
+            }
             foreach(var address in message.ToEmails)
             {
                 smtpMessage.To.Add(new MailAddress(address));