Step 2: Configure Postfix to use a content filter
The next step is to configure Postfix to use DSPAM as a content filter.
This is relatively simple and requires only a minor change to your
master.cf file:
Change:
smtp inet n - n - - smtpd
To:
smtp inet n - n - - smtpd
-o content_filter=lmtp:unix:/tmp/dspam.sock
This tells Postfix to send all mail to DSPAM for content filtering.
Step 3: Configure a Reinjection Port
You'll also need to configure Postfix to listen on a local port for
reinjection. This is where DSPAM sends back the "good" mail (or alternatively,
tagged mail also). Add this to your master.cf:
localhost:10026 inet n - n - - smtpd
-o content_filter=
-o receive_override_options=no_unknown_recipient_checks,no_header_body_checks
-o smtpd_helo_restrictions=
-o smtpd_client_restrictions=
-o smtpd_sender_restrictions=
-o smtpd_recipient_restrictions=permit_mynetworks,reject
-o mynetworks=127.0.0.0/8
-o smtpd_authorized_xforward_hosts=127.0.0.0/8
Any mail sent to localhost:10026 will be delivered in whatever way you
have configured Postfix, without being passed through DSPAM again. This is
also where DSPAM will deliver false positives to when they are retrained by
the user.