How to block/permit all email sent from a particular IP/range in Postfix

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux
  • Postfix

Issue

  • How to permit only some hosts or subnets to send mail

Resolution

Steps below would allow only subnet 10.0.0.0/24 and host 10.0.1.15 to send mail through the server.

  1. Make sure /etc/postfix/access file exist and has following lines:

    10.0.1.15 OK
10.0.0.0/24 OK

  2. Run postmap against /etc/postfix/access file

    # postmap  /etc/postfix/access

  3. Setup the smtpd_client_restrictions in the /etc/postfix/main.cf to allow only mynetworks and IP addresses from the /etc/postfix/access

    smtpd_client_restrictions = permit_mynetworks, check_client_access cidr:/etc/postfix/access, reject

  4. Restart postfix service

    # service postfix restart

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