How To Whitelist Hosts/IP Addresses In Postfix

Version 1.0
Author: Falko Timme <ft [at] falkotimme [dot] com>

If you are administrating a mail server and use blacklists to block spam (like in this article: How To Block Spam Before It Enters The Server (Postfix)), you probably know this problem: from time to time your customers complain that they cannot receive emails from certain freemailers. Most often this happens because a freemailer was abused to send out spam and therefore got blacklisted. This short guide shows how you can whitelist such a mail server in Postfix to make your customers happy again.

I do not issue any guarantee that this will work for you!


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If a blacklisted server tries to send mail to your server, you should find something like this in your mail log:

SMTP error from remote mail server after RCPT TO:<>: host []: 554 5.7.1 Service unavailable; Client host [] blocked using; Currently Sending Spam See:

In this example, the mail server is blacklisted and therefore blocked.


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