I have an email server running Postfix. Everything is working fine, However, recently, some internal emails received emails from their own addresses with phishing content. After finding out, I learned that Postfix can send internal emails using telnet port 25, sending it internally in my domain does not require authentication. I got the idea of enabling authentication with local domain emails, I searched but got no answer. I appreciate the help Sorry my English is not good so I have to use google translate
It's alerting that someone from the localhost is able to send phishing mail: it means someone is already inside the system or there's e.g. a web application that enables those connections. You shouldn't accept this, but carefully investigate where it's coming from and stop it.
That said, to answer your question, there's nothing special with local delivery regarding SMTP on port
25. Removing this permission could be done (in the
main.cf) simply by either
- removing the
- removing the
127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128from
However, with this your local users must use the submission port(s) to deliver their mail. The authenticated users can by default use any address as an envelope sender. To limit this, the
smtps services in
master.cf should have:
-o smtpd_sender_login_maps=hash:/etc/postfix/virtual -o smtpd_sender_restrictions=reject_sender_login_mismatch
hash:/etc/postfix/virtual is the same that is used for
virtual_alias_maps, because it already has the required
firstname.lastname@example.org username format with the correct address to user mappings.