Pop3

Opensuse
Postfix
ispconfig

I would like to limit pop3 connections to three areas.

  1. local, like 192. something

  2. top domain for my Internet connection, like 204. something.

  3. top domain for one other, like 270. something.

What would be the easiest/best way to do this?
Firewall?
Mail server?

Thanks in advance for reading this.

I would use the firewall route. Simple and fast.