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

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

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

Sure, but competition is good for the user.

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.

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.

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