Noel Jones wrote:
Use a check_client_access map to control what IPs can send mail to your
server.
# main.cf
smtpd_client_restrictions =
check_client_access cidr:/etc/postfix/allowed_clients
# reject all unlisted clients
reject
Andrew, is your server listed as a secondary MX for the domains in question?
If your server is listed as a MX host officially in DNS, you should IMHO
not use plain "reject" there, but rather a 4** error message to make
sure that clients connect to the primary MX instead. As far as I can
tell, "reject" would force the clients to give up on that message
completely and bounce it to the sender.
Hope this helps,
wolfgang