Merge pull request #5132 from JediKev/issue/umlauts-subject-line

issue: Umlauts In Subject

include/class.format.php

@@ -43,6 +43,11 @@ class Format {
     }
 
     function mimedecode($text, $encoding='UTF-8') {
+        // Handle poorly or completely un-encoded header values (
+        if (function_exists('mb_detect_encoding'))
+            if (($src_enc = mb_detect_encoding($text))
+                    && (strcasecmp($src_enc, 'ASCII') !== 0))
+                return Charset::transcode($text, $src_enc, $encoding);
 
         if(function_exists('imap_mime_header_decode')
                 && ($parts = imap_mime_header_decode($text))) {