I don't expect an overnight change of all desktops to what the US Military used to call B3 level security. And even that would not stop users from shooting themselves into the foot.

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

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

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.

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.

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