Index: lib/Mail/mimePart.php
===================================================================
--- lib/Mail/mimePart.php       (revision 2653)
+++ lib/Mail/mimePart.php       (working copy)
@@ -186,7 +186,7 @@
         if (isset($contentType['type'])) {
             $headers['Content-Type'] = $contentType['type'];
            if (isset($contentType['charset'])) {
-                $headers['Content-Type'] .= " charset={$contentType['charset']}";
+                $headers['Content-Type'] .= "; charset={$contentType['charset']}";
             }
             if (isset($contentType['name'])) {
                 $headers['Content-Type'] .= ';' . MAIL_MIMEPART_CRLF;