Drop References header if In-Reply-To is modified by user. Closes #3221.

2 files changed, 10 insertions, 4 deletions

diff --git a/doc/manual.xml.head b/doc/manual.xml.head
index 616e7a3e..e684d0af 100644
--- a/doc/manual.xml.head
+++ b/doc/manual.xml.head
@@ -1387,7 +1387,7 @@ permanently. The selection can later be changed in the compose menu.
 
 <para>
 When replying to messages, the <emphasis>In-Reply-To:</emphasis> header contains the
-Message-Id of the message(s) you reply to. If you remove its value, Mutt will not generate a
+Message-Id of the message(s) you reply to. If you remove or modify its value, Mutt will not generate a
 <emphasis>References:</emphasis> field, which allows you to create a new message thread, for example
 to create a new message to a mailing list without having to enter the mailing list's address.
 </para>
diff --git a/headers.c b/headers.c
index 62a7c672..ac8bfac4 100644
--- a/headers.c
+++ b/headers.c
@@ -110,6 +110,15 @@ void mutt_edit_headers (const char *editor,
   safe_fclose (&ifp);
   mutt_unlink (path);
 
+  /* in case the user modifies/removes the In-Reply-To header with
+     $edit_headers set, we remove References: as they're likely invalid;
+     we can simply compare strings as we don't generate Refereces for
+     multiple Message-Ids in IRT anyways */
+  if (!n->in_reply_to || (msg->env->in_reply_to &&
+			  mutt_strcmp (n->in_reply_to->data,
+				       msg->env->in_reply_to->data) != 0))
+    mutt_free_list (&msg->env->references);
+
   /* restore old info. */
   mutt_free_list (&n->references);
   n->references = msg->env->references;
@@ -118,9 +127,6 @@ void mutt_edit_headers (const char *editor,
   mutt_free_envelope (&msg->env);
   msg->env = n; n = NULL;
 
-  if (!msg->env->in_reply_to)
-    mutt_free_list (&msg->env->references);
-
   mutt_expand_aliases_env (msg->env);
 
   /* search through the user defined headers added to see if