In this episode I talk about some basic firewall rules that many organizations don’t have in place.
- Block outbound port TCP 25 for all devices except your mail server(s).
- If you use a third party mail filter like Postini or Securence, ensure that only their IPs are allowed to send mail directly to your environment.
- Check your mail server config as far as what devices are allowed to relay anonymously to the outside world.
- Take advantage of outbound smarthosting to filter outgoing spam.