This will surprise some of your readers, but my primary interest is not with computer security. I am primarily interested in writing software that works as intended.

As of today, the Postfix mail transport agent has almost 50,000 lines of code, comments not included.

Coming back to the topic of computer security, the TCP Wrapper is an example of such a safety net. I wrote it when my systems were under attack by someone who appeared to walk through walls.

When I write software, I know that it will fail, either due to my own mistake, or due to some other cause.

I want to avoid locking people into solutions that work only with Postfix. People should have a choice in what software they want to use with Postfix, be it anti-virus or otherwise.

Postfix keeps running even if one Postfix process dies; Windows requires that someone restarts the service.

Like all software, Qmail can survive only when it keeps up with changing requirements.