HI
I haven't worked out whats causing your problem, however I do know the stack trace is the from the
code base in the 1.5.3 pre-release SDK.
A step you can take to remedy the situation would involve
modifying your own handler and putting a try block around the receive method
and trap the InvalidEmailError and log the mail contents.
You can then see where the offending email is coming from.
I am guessing because the exception isn't trapped the mail goes back in a queue for delivery
so by trapping the exception, you can stop it from being re-delivered.
Hope this helps
Rgds