How to Enforce Sender Address in Postfix

linuxpostfixsmtp-auth

I have set up a Postfix server with SMTP AUTH (STARTTLS on port 587). All my users are in the domain "example.org". I want to enforce the sender address to be "logged-in-user@example.org".

I learned that this can be achieved with the main.cf options

smtpd_sender_restrictions = reject_sender_login_mismatch, ...
smtpd_sender_login_maps = hash:/etc/postfix/smtpd_sender_login_maps

with a login_maps file like:

a@example.org a
b@example.org b
c@example.org c
...

(see also Block sender address spoofing with SMPT AUTH), but this would mean I'll have to edit the login_maps file every time I have a new user. I don't need such a flexible mapping: It should always be "logged-in-user@example.org". Is there an easier option?

Best Answer

First, check whether your installation of Postfix supports pcre by entering the command postconf -m and looking for a line with pcre in it. Once you have verified that you have pcre support, you can do as follows:

/etc/postfix/login_maps.pcre:

/^(.*)@example\.org$/   ${1}

In main.cf:

smtpd_sender_login_maps = pcre:/etc/postfix/login_maps.pcre

This should work fine.

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