Configuring the postfix - Avoid unauthorized access

First of all, we start at /etc/postfix/main.cf file and adding this:


Here you got the explanations - www.postfix.org/postconf.5.html#smtpd_sender_restrictions

Then we need the access file, which should be at the postfix directory. (explanations -> www.postfix.org/access.5.html)
In this file, we start to list domains/mails/patterns and actions to take after postfix will read that. So, I just needed domains for now and it looks like this:

After that we need to postmap the file access, so run:

After all, restart postfix:

service postfix restart

To check if domain is blocked, you can create domain block for your private mail (for ex. gmail.com, yahoo.com, etc.) and see the action in /var/log/maillogThere should be: [...] Sender address rejected: Access denied; [...]