deoren:
> Is there a way to accomplish what the Linux Email book mentions?
> Basically restricting use of your domain to your clients/backup
> MX and using a custom response or log message to indicate what
> rule blocked offenders?
/etc/postfix/main.cf:
smtpd_client_restrictions =
permit_mynetworks permit_sasl_authenticated reject
This will block mail with "access denied". If that is not sufficient:
/etc/postfix/main.cf:
smtpd_reject_footer = \c. See http://www.example.com/mail-reject. blah blah.
This will append the specified text to reject responses.
http://www.postfix.org/postconf.5.html#smtpd_reject_footer
You can provide custom responses with access maps but no-one is
going to look at that stuff, and many email readers don't even show
it to the user.
Wietse