Index: /trunk/roundcubemail/program/include/rcube_imap_generic.php
===================================================================
--- /trunk/roundcubemail/program/include/rcube_imap_generic.php	(revision 4485)
+++ /trunk/roundcubemail/program/include/rcube_imap_generic.php	(revision 4486)
@@ -1632,5 +1632,5 @@
                         case 'content-type':
                             $ctype_parts = preg_split('/[; ]/', $string);
-                            $result[$id]->ctype = array_shift($ctype_parts);
+                            $result[$id]->ctype = strtolower(array_shift($ctype_parts));
                             if (preg_match('/charset\s*=\s*"?([a-z0-9\-\.\_]+)"?/i', $string, $regs)) {
                                 $result[$id]->charset = $regs[1];