Index: mimemail.inc
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/mimemail/mimemail.inc,v
retrieving revision 1.44
diff -u -r1.44 mimemail.inc
--- mimemail.inc	21 Apr 2010 23:24:22 -0000	1.44
+++ mimemail.inc	19 Jun 2010 16:33:17 -0000
@@ -248,7 +248,9 @@
         $part_headers['Content-Disposition'] .= '; filename="'. $part['name'] .'"';
       }
 
-      $part_body = chunk_split(base64_encode(file_get_contents($part['file'])));
+      if (isset($part['file'])) {
+        $part_body = chunk_split(base64_encode(file_get_contents($part['file'])));
+      }
     }
 
     $body .= "\n--$boundary\n";