* minor cs

* fixed #1484712

program/lib/imap.inc

@@ -1571,8 +1571,10 @@ function iil_C_FetchHeaders(&$conn, $mailbox, $message_set, $uidfetch=false) {
 					 	$ctype_parts = explode(";", $string);
 						$result[$id]->ctype = array_shift($ctype_parts);
 						foreach ($ctype_parts as $ctype_add)
-							if (preg_match('/charset="?([a-z0-9\-]+)"?/i', $ctype_add, $regs))
+                            if (preg_match('/charset="?([a-z0-9\-\.\_]+)"?/i',
+                                $ctype_add, $regs)) {
                                 $result[$id]->charset = $regs[1];
+							}
                             break;
 					case 'in-reply-to':
 						$result[$id]->in_reply_to = ereg_replace("[\n<>]", '', $string);