Score:0

Postfix - Auth restriction with multiple servers

lr flag

I'm running two mailservers for one domain. One of them is a Microsoft Exchange server that holds a few mail accounts - and a Postfix one hosted on my Linux server to which mails are relayed from Exchange, if the recipient doesn't exist there.

I would like to use reject_authenticated_sender_login_mismatch on my Postfix server. I want to make sure, that no one sends emails from adresses that they don't own. Now the problem comes up: it doesn't reject the emails relayed from Exchange, but it rejects emails sent from Exchange to an account that lies on Postfix.

I hope it's clear what I mean. I don't even get why this commands verifies incoming mails. All I want to control is outbound.

Score:1
jp flag

You have probably put the configuration parameter in your main.cf, making it a global setting for all smtpd instances.

The instance on port 25 should be handling inbound mail without this setting, while another instance for submission on SMTPS port 465 (or STARTTLS on 587) handles outbound mail from your own users. Using the master.cf you can add configuration parameters for individual instances.

P123 avatar
lr flag
Thank you, that was the reason!
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