Fix dummy Message-Id when resuming a draft without Message-Id header (#6548)

CHANGELOG

@@ -44,6 +44,7 @@ CHANGELOG Roundcube Webmail
 - Fix listing the same attachment multiple times on forwarded messages
 - Fix bug where a message/rfc822 part without a filename wasn't listed on the attachments list (#6494)
 - Fix inconsistent offset for various time zones - always display Standard Time offset (#6531)
+- Fix dummy Message-Id when resuming a draft without Message-Id header (#6548)
 
 RELEASE 1.4-beta
 ----------------

program/steps/mail/compose.inc

@@ -227,7 +227,9 @@ if (!empty($msg_uid) && empty($COMPOSE['as_attachment'])) {
                 }
             }
 
-            $COMPOSE['param']['message-id'] = $MESSAGE->headers->get('message-id');
+            if (($msgid = $MESSAGE->headers->get('message-id')) && !preg_match('/^mid:[0-9]+$/', $msgid)) {
+                $COMPOSE['param']['message-id'] = $msgid;
+            }
 
             // use message UID as draft_id
             $OUTPUT->set_env('draft_id', $msg_uid);