From 1fcc65235825ef7ce6833eed2c19ddcce7014a53 Mon Sep 17 00:00:00 2001
From: M66B <M66B@users.noreply.github.com>
Date: Tue, 20 Nov 2018 16:51:51 +0100
Subject: [PATCH] Add thread ID header

---
 app/src/main/java/eu/faircode/email/MessageHelper.java | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/app/src/main/java/eu/faircode/email/MessageHelper.java b/app/src/main/java/eu/faircode/email/MessageHelper.java
index 0da03a7a80..b31b6cead5 100644
--- a/app/src/main/java/eu/faircode/email/MessageHelper.java
+++ b/app/src/main/java/eu/faircode/email/MessageHelper.java
@@ -188,6 +188,8 @@ public class MessageHelper {
             imessage.addHeader("References", (replying.references == null ? "" : replying.references + " ") + replying.msgid);
         }
 
+        imessage.addHeader("X-FairEmail-Thread", message.thread);
+
         imessage.setFlag(Flags.Flag.SEEN, message.seen);
 
         if (message.from != null && message.from.length > 0) {
@@ -376,6 +378,10 @@ public class MessageHelper {
     }
 
     String getThreadId(long uid) throws MessagingException {
+        String[] xThread = imessage.getHeader("X-FairEmail-Thread");
+        if (xThread != null && xThread.length > 0)
+            return xThread[0];
+
         for (String ref : getReferences())
             if (!TextUtils.isEmpty(ref))
                 return ref;