Shout-out to Linux Babe

Xiao Guoan runs a great site here: https://www.linuxbabe.com/ If you want help with best practices for email spam reduction she has a great post here: https://www.linuxbabe.com/redhat/blocking-email-spam-postfix-centos My $.02 on this is adding to her smtpd_helo_restrictions. I recommend sender_access as it is a standard and can be used elsewhere like this:

smtpd_helo_restrictions =
        permit_mynetworks
        permit_sasl_authenticated
        check_sender_access hash:/etc/postfix/sender_access
        reject_invalid_helo_hostname
        reject_non_fqdn_helo_hostname
        reject_unknown_helo_hostname

This allows you to easily whitelist stupid email admins that don’t understand DNS. The format for sender_access is:

[email protected]   OK
example1.com    OK
example2.com    REJECT SPAM
[email protected]    REJECT
[email protected]    550 Blacklisted

Leave a Reply

Your email address will not be published.