Fix broken encoding of HTML content encapsulated in a RTF attachment (#8444)

CHANGELOG.md

@@ -14,6 +14,7 @@
 - Fix handling of message/rfc822 parts that are small and are multipart structures with a single part (#8458)
 - Fix bug where session could time out if DB and PHP timezone were different (#8303)
 - Fix bug where DSN flag state wasn't stored with a draft (#8371)
+- Fix broken encoding of HTML content encapsulated in a RTF attachment (#8444)
 
 ## Release 1.5.2
 

program/lib/Roundcube/rcube_message.php

@@ -1099,6 +1099,7 @@ class rcube_message
             $tpart->mime_id         = 'winmail.' . $part->mime_id . '.html';
             $tpart->size            = strlen($tnef_arr['message']);
             $tpart->body            = $tnef_arr['message'];
+            $tpart->charset         = RCUBE_CHARSET;
 
             $parts[] = $tpart;
         }