If you happen to be running your own Postfix mail server and you are wanting to add a little filtering to the incoming mail, then here's some advice that will get you up and running in no time…
1. Copy the blacklist sa-blacklist.current.reject to a sensible spot…
/etc/postfix/sender_restrictions seams reasonable.
2. Update main.cf, adding the line:
smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/sender_restrictions
3. Create the access table hash:
sudo postmap /etc/postfix/sender_restrictions
4. Have the master daemon reread main.cf:
sudo postfix reload
You are now rejecting envelope senders from the blacklisted domains, they will be rejected with a 554 error. If you would like to test this without actually rejecting mails, you can add `warn_if_reject, ' before the `check_sender_access' token, messages that would be rejected will be logged with a `reject_warning'.