Index: program/include/rcube_imap.php
===================================================================
--- program/include/rcube_imap.php	(revision 322b79db06cfd0d9a0ca5c63536c36265d5ce7d2)
+++ program/include/rcube_imap.php	(revision 73ba7caadb53733a039dc797768227b042798803)
@@ -1365,4 +1365,6 @@
       
     // TODO: Add caching for message parts
+
+    if (!$part) $part = 'TEXT';
 
     if ($print)