I needed to add some more ‘security’ to our mail chain, which required adding more checking on the MX Proxy, which is our host that sits on the Internet ‘proxying’ mail traffic in and out of the organisation.
To improve our security profile, using our preferred Postfix, necessitates incoming mail be processed independently of outgoing mail.
Read more of what we were able to do in
MX Proxy Extended, using Multiple Instances
To save money on a 2nd computer hardware and using another Public IP address, we used Postfix’s Multiple Instance facilities, as well as using separate ports for internal mail and external mail.