Qmail out of the box works fine, so people will want to use it regardless of licensing restrictions, even when the software does not ship with their system software.

The Postfix security model is based on keeping software simple and stupid.

However, writing software without defects is not sufficient. In my experience, it is at least as difficult to write software that is safe - that is, software that behaves reasonably under adverse conditions.

The challenge with Postfix, or with any piece of software, is to update software without introducing problems.

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

Defect-free software does not exist.

For many people my software is something that you install and forget. I like to keep it that way.