Fix regression where drafts were not deleted after sending the message (#6756)

CHANGELOG

@@ -91,6 +91,7 @@ RELEASE 1.4-rc1
 - Elastic: Add selection options on contacts list (#6595)
 - Elastic: Fix unintentional layout preference overwrite (#6613)
 - Log errors caused by low pcre.backtrack_limit when sending a mail message (#6433)
+- Fix regression where drafts were not deleted after sending the message (#6756)
 - Fix so max_message_size limit is checked also when forwarding messages as attachments (#6580)
 - Fix so performance stats are logged to the main console log also when per_user_logging=true
 - Fix malformed message saved into Sent folder when using big attachments and low memory limit (#6498)

program/include/rcmail_sendmail.php

@@ -363,6 +363,8 @@ class rcmail_sendmail
      * Message delivery, and setting Replied/Forwarded flag on success
      *
      * @param Mail_mime $message Message object
+     *
+     * @return bool True on success, False on failure
      */
     public function deliver_message($message)
     {
@@ -383,14 +385,16 @@ class rcmail_sendmail
             }
 
             if ($smtp_error && is_string($smtp_error)) {
-                return $this->options['error_handler']($smtp_error, 'error');
+                $this->options['error_handler']($smtp_error, 'error');
             }
             else if ($smtp_error && !empty($smtp_error['label'])) {
-                return $this->options['error_handler']($smtp_error['label'], 'error', $smtp_error['vars']);
+                $this->options['error_handler']($smtp_error['label'], 'error', $smtp_error['vars']);
             }
             else {
-                return $this->options['error_handler']('sendingfailed', 'error');
+                $this->options['error_handler']('sendingfailed', 'error');
             }
+
+            return false;
         }
 
         $message->mailbody_file = $mailbody_file;
@@ -417,6 +421,8 @@ class rcmail_sendmail
                 }
             }
         }
+
+        return true;
     }
 
     /**