can i detect if any authenticated user try sends a mail from another email address so that i can do an Action before we are on a blacklist?
so i mean the postfix option reject_sender_login_mismatch
i have added reject_sender_login_mismatch to smtpd_sender_restrictions (before check_sender_access) but if i restart postfix, i get this error with each user...
Jun 3 14:34:27 mail01 postfix/smtpd: NOQUEUE: reject: RCPT from ***: 553 5.7.1 <firstname.lastname@example.org>: Sender address rejected: not owned by user USER@domain; from=<email@example.com> to=<firstname.lastname@example.org> proto=ESMTP helo=<ul.raving.at>
Originally Posted by till
Then either someone got the login details of the account over a unencrypted connection or the computer of the user has been hacked. In any case, you will have to change the password of the account to stop the spam.
The user may use any sender address, after authentication.