qmail

Seeing Qmail rot on the vine is heart-breaking, but that's exactly what happened.

If you're running qmail processes without data size rlimits, you're vulnerable to resource-exhaustion denial-of-service attacks in any case.

There was one potential security bug (Guninski’s find), which was probably not exploitable on any installation of qmail.

They haven't caught up to Daniel Bernsteins' Qmail claims much less top-tier work like KeyKOS [1] or Burroughs [2].

The other is in a process that already runs as root, although for POP, which was a thing I didn't run when I ran qmail.

Lots of successful projects are rewrites or clones of existing software, like QMail over Sendmail and vim itself over vi.

Changing the implementation or not allowing ANY queries at all breaks things, qmail for one iirc.

Yes, others (including qmail) existed but sendmail was, by far, the most widely used.

Postfix, Sendmail, exim, and qmail can all be configured to strictly adhere to standards.

Back when I started as a sysadmin chroot jails with bind, qmail etc were all the rage.

There are established guides to configuring qmail that tell you to set rlimits.

Nobody uses the OS to set process limits like djb claimed (nor should they), so it was exploitable on any installation of qmail.

Wasn't the "de facto standard" set by QMail back in 1998?

He stopped working on it once he had a solution that passed his test without segfaulting immediately." Anecdotal, please provide a link to the qmail mailing list with evidence.

I used to use Qmail exclusively, but over time it got harder and harder to install an up-to-date version of it, requiring more and more "unofficial" patches to get it actually working.

They serve as art pieces more than practical, useful software." There are plenty of "maintainers", just search for the qmail mailing list, if that is impossible then I'm not sure what to say to you, but what you say is bunk.