Did you try all 3 methods of integration? Just curious because if not... perhaps one of the other methods would do the trick.
As a delivery proxy:
The default approach integrates DSPAM directly with the mail server and
filters spam as mail comes in. Please see the appropriate instructions
in doc/ pertaining to your MTA.
As a POP3 proxy:
This alternative approach implements a POP3 proxy where users
connect to the proxy to check their email, and email is filtered when
being downloaded. The POP3 proxy is a much easier approach, as it
requires much less integration work with the mail server (and is ideal
for implementing DSPAM on Exchange, etcetera). Please see the file
As an SMTP Relay:
DSPAM can be configured as an SMTP relay, a.k.a appliance. You
can set it up to sit in front of your real mail server and then point
your MX records at it. DSPAM will then pass along the good mail to
your real SMTP server. See doc/relay.txt for more information. The
example provided uses Postfix and MySQL.