From b397a1fdcd2771154623319d73b3094044527565 Mon Sep 17 00:00:00 2001
From: Ryan Tregea <ryan@biztactix.com.au>
Date: Sun, 6 Aug 2017 12:44:38 +1000
Subject: [PATCH 1/2] Add References and InResponseTo Headers

Add Headers for References and InResponseTo
They were previously ignored, which prevented Office 365 correctly Threading return messages sent.
---
 src/Typesafe.Mailgun/FormPartsBuilder.cs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/Typesafe.Mailgun/FormPartsBuilder.cs b/src/Typesafe.Mailgun/FormPartsBuilder.cs
index 9793df1..9689f0b 100644
--- a/src/Typesafe.Mailgun/FormPartsBuilder.cs
+++ b/src/Typesafe.Mailgun/FormPartsBuilder.cs
@@ -78,6 +78,26 @@ public static List<FormPart> Build(MailMessage message, IDictionary<string, IDic
 					}
 				}
 			}
+			
+			if (message.Headers.AllKeys.Contains("References"))
+			{
+				// Grab the References Header
+				var References = message.Headers.GetValues("References");
+				if (References != null)
+				{
+					result.Add(new SimpleFormPart("h:References", References));
+				}
+			}
+			
+			if (message.Headers.AllKeys.Contains("In-Reply-To"))
+			{
+				// Grab the References Header
+				var inReplyTo = message.Headers.GetValues("In-Reply-To");
+				if (inReplyTo != null)
+				{
+					result.Add(new SimpleFormPart("h:In-Reply-To", inReplyTo));
+				}
+			}
 
 			result.AddRange(message.Attachments.Select(attachment => new AttachmentFormPart(attachment)));
 

From 925316c16b3d5c49624307fcc2f933f1709d2837 Mon Sep 17 00:00:00 2001
From: "AzureAD\\RyanTregea" <Ryan@biztactix.com.au>
Date: Sun, 6 Aug 2017 17:03:44 +1000
Subject: [PATCH 2/2] Makes it work....

---
 src/Typesafe.Mailgun/FormPartsBuilder.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Typesafe.Mailgun/FormPartsBuilder.cs b/src/Typesafe.Mailgun/FormPartsBuilder.cs
index 9689f0b..a207ef1 100644
--- a/src/Typesafe.Mailgun/FormPartsBuilder.cs
+++ b/src/Typesafe.Mailgun/FormPartsBuilder.cs
@@ -82,7 +82,7 @@ public static List<FormPart> Build(MailMessage message, IDictionary<string, IDic
 			if (message.Headers.AllKeys.Contains("References"))
 			{
 				// Grab the References Header
-				var References = message.Headers.GetValues("References");
+				var References = message.Headers["References"];
 				if (References != null)
 				{
 					result.Add(new SimpleFormPart("h:References", References));
@@ -92,7 +92,7 @@ public static List<FormPart> Build(MailMessage message, IDictionary<string, IDic
 			if (message.Headers.AllKeys.Contains("In-Reply-To"))
 			{
 				// Grab the References Header
-				var inReplyTo = message.Headers.GetValues("In-Reply-To");
+				var inReplyTo = message.Headers["In-Reply-To"];
 				if (inReplyTo != null)
 				{
 					result.Add(new SimpleFormPart("h:In-Reply-To", inReplyTo));