Index: mailgw.py
===================================================================
--- mailgw.py	(revision 4520)
+++ mailgw.py	(working copy)
@@ -82,6 +82,7 @@
 import traceback, rfc822
 
 from email.Header import decode_header
+from traceback import format_exc
 
 from roundup import configuration, hyperdb, date, password, rfc2822, exceptions
 from roundup.mailer import Mailer, MessageSendError
@@ -1383,9 +1384,10 @@
                             'property %(prop)s of class %(classname)s.') % locals()
                 nodeid = cl.create(**props)
         except (TypeError, IndexError, ValueError, exceptions.Reject), message:
+            exc = format_exc ()
             raise MailUsageError, _("""
 There was a problem with the message you sent:
-   %(message)s
+   %(message)s\n%(exc)s
 """) % locals()
 
         # commit the changes to the DB