letter rip pro and qmail

[[EMAIL PROTECTED]]

Has anyone on the list had any problems getting qmail to accept mail
deliveries from someone using letter rip pro?  I have a user who is using
letter rip, but his session is "unexpectedly closed" every time when trying
to send mail to my server.  The domain he is trying to send to is hosted on
my mail machine, and has no problems receiving mail from any other source.
Any ideas?

Brendan