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.

Defect-free software does not exist.

Most of the effort in the software business goes into the maintenance of code that already exists.

Writing software that's safe even in the presence of bugs makes the challenge even more interesting.

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.

One bug in an SMTP server can open up the whole machine for intrusion.

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