If you are sure…
So, if you are sure you want to block all mail to/from the list of domains, you can add the following directive to your postfixfile:
smtpd_sender_restrictions = hash:/etc/postfix/access reject_unauth_destination = hash:/etc/postfix/access
Once this has been added to the, you need to create the /etc/postfix/access file and put entries in it like this:
REJECT REJECT REJECT
So on and so forth until all the domains have been entered. Once you have created this file and the permissions are correct run the following command:
and finally restart postfix.