From 4bb7928319a352fc2134166a36d498acaaaede35 Mon Sep 17 00:00:00 2001
From: M66B <M66B@users.noreply.github.com>
Date: Sat, 8 Dec 2018 14:04:15 +0100
Subject: [PATCH] Fallback to in-reply-to for thread ID when no references

---
 app/src/main/java/eu/faircode/email/MessageHelper.java | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/app/src/main/java/eu/faircode/email/MessageHelper.java b/app/src/main/java/eu/faircode/email/MessageHelper.java
index 61afdd4e46..d8ebd032e5 100644
--- a/app/src/main/java/eu/faircode/email/MessageHelper.java
+++ b/app/src/main/java/eu/faircode/email/MessageHelper.java
@@ -402,6 +402,10 @@ public class MessageHelper {
             if (!TextUtils.isEmpty(ref))
                 return ref;
 
+        String inreplyto = getInReplyTo();
+        if (inreplyto != null)
+            return inreplyto;
+
         String msgid = getMessageID();
         return (TextUtils.isEmpty(msgid) ? Long.toString(uid) : msgid);
     }