Index: mimemail.module
===================================================================
--- mimemail.module	(revision 474)
+++ mimemail.module	(working copy)
@@ -364,6 +364,11 @@
     $subject = $message['subject'];
     if ($format = variable_get('mimemail_format', FILTER_FORMAT_DEFAULT)) {
       $body = check_markup($message['body'], $format);
+      # check_markup returns 'n/a' if the current user doesn't have
+      # permission to use $format.
+      if (($body == t('n/a')) && ($format != FILTER_FORMAT_DEFAULT)) {
+        $body = check_markup($message['body'], FILTER_FORMAT_DEFAULT);
+      }
     }
     else {
       $body = $message['body'];