The following main.cf, thanks to Noel, blocks mail whose
DNS is misconfigured as follows.
1.) IP -> nothing
2.) IP -> domain -> nothing
3.) IP -> domain -> IP2
It accepts only mail where
4.) IP -> domain -> IP
I find that 1 and 2 block most of the spam, and very little
bad mail comes in via 3.
I would like to automatically let all mail through where
IP -> domain -> IP2
There are a small number of valid mail servers that are
misconfigued, like when the server's IP changes, and the admin
forgets to set the domain -> to the new IP.
Periodically my large corp customers ask me to white list
IP's or domain names because they aren't getting valid mail.
and the misconfigurations are always of this type.
Pointers to RTFM are welcome.
Homer W. Smith
CEO Lightlink Internet
smtpd_delay_reject = yes
smtpd_helo_required = yes
smtpd_helo_restrictions =
permit_mynetworks,
check_helo_access hash:/etc/postfix/check_helo_access,
permit
smtpd_client_restrictions=
check_client_access hash:/etc/postfix/rbl_override
reject_unknown_client_hostname
reject_rbl_client bl.spamcop.net
smtpd_sender_restrictions =
check_sender_access hash:/etc/postfix/sender_access
reject_unknown_sender_domain
smtpd_recipient_restrictions =
permit_mynetworks
permit_sasl_authenticated
reject_unauth_destination
check_recipient_access hash:/etc/postfix/recipient_access
check_policy_service inet:127.0.0.1:10023
