[Mimedefang] Repeated messages

[Stefano McGhee]

Hello all,
	Has anyone experienced behavior where messages through MIMEDefang
are resent over and over again?  Examples scenario:  

My user sends an email with an incorrect email address to an external
address (i.e. somebody at bigcorp.com).  The user misspells the persons name
(oopsbody at bigcorp.com) and the server politely returns the message as
undeliverable, claiming not to know who the message is for.  My user gets
the NDR just fine, but KEEPS getting it (the NDR) every few hours.  It
turns out that the message is being resent by the other server over and
over again because our server doesn't acknowledge the message properly.  It
seems to only happen with some NDRs and messages with large file
attachments.  Any ideas?

Cheers and Thanks,

Stefano