Description:

  • Configure your DNS server to include SPF records for your domain.
  • The only acceptable as a source of e-mail from your domain is your server.
  • The SPF record should reflect this.

Implementation:

  1. Add line to /etc/bind/db.d4.sysinst.ida.liu.se: @ IN TXT "v=spf1 mx -all"
  2. Restart service: service bind9 reload

Verification:

  • dig d4.sysinst.ida.liu.se TXT should return the above line
  • Sending an email from server.d4.sysinst.ida.liu.se to e.g. a gmail should have a ‘Received-SPF: pass’ in the header.
  • Sending an email from another client should have a ‘Received-SPF: fail’ in the header