Configure Incoming Filtering with Postfix

  1. Create the file /etc/postfix/access with the content:
    2. 
antispamcloud.com OK
  2. Execute the command:

    3. postmap /etc/postfix/access

  3. Either:
    1. Add the following to /etc/postfix/main.cf
      smtpd_client_restrictions = check_client_access hash:/etc/postfix/access, 
permit_mynetworks, reject

      2. OR

    2. If you already have smtpd_client_restrictions defined in /etc/postfix/main.cf, insert the following at the beginning of your definition and replace permit with reject at the end of definition:

      "check_client_access hash:/etc/postfix/access"

  4. Reload the Postfix configuration by executing the following command:

    5. sudo postfix reload

  5. Restart Postfix by executing the following command:

    6. /etc/init.d/postfix restart

Per domain setup

It's also possible with Postfix to configure the MTA to only allow connections from the Spam Experts servers for specific protected domains:

  1. Add the following to the main.cf
    2. smtpd_restriction_classes = Spam ExpertsSpam Experts = check_client_access hash:/etc/postfix/Spam Experts, reject
smtpd_recipient_restrictions = check_recipient_access hash:/etc/postfix/protected_destinations, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
  2. Create the following file:
    3. /etc/postfix/Spam Experts
    1. Add the following content:
      2. antispamcloud.com OK

      If you send or receive any internal mail, you will need to also add your domain, localhost and the local domain in the following format:
      demo-domain.invalid OK
      localhost OK
      localdomain OK

  3. Create the following file:

    4. /etc/postfix/protected_destinations

    1. Add the domains that you want to configure:

      2. demo-domain.invalid Spam Experts

  4. Postmap both files:

    5. postmap /etc/postfix/Spam Experts

    postmap /etc/postfix/protected_destinations

  5. Reload the Postfix configuration by executing the following command:

    6. sudo postfix reload

  6. Restart Postfix by executing the following command:

    7. /etc/init.d/postfix restart

Local Cloud

Replace antispamcloud.com with your servers root hostname.