So...are you running an open SMTP relay, or are you refusing to relay mail for your own users? Because I'm pretty sure that with an unpatched qmail, you've got to be doing one or the other.
Not using qmail the way you are (incorrectly) assuming.
I am an end user not an email provider.
For example I use qmail to provide "inter-device email" on a local network of devices all belonging to the same user, and not connected to the internet. Not that I love email but these devices are sometimes "locked down" by default and email is one of the few ways to move files between devices without using the internet.
Another example is using qmail on a tap-based layer 2 overlay (not OpenVPN) to provide encrypted "peer-to-peer email". Each peer is running qmail-smtpd bound to a tap device. This was an experiment to prove encrypted email is easy.
qmail running under curvecpserver is another experiment.
Advice for all commenters who make presumptions about others computer use: Please kindly check your assumptions.
1 Is this an issue for musl and the various other alternatives to glibc? I have no idea but seems like only referring to glibc 2.3.x and up is a bit myopic. Its possible some users might not be using that library. I am one such user.
Instead everybody is running "qmail" which is qmail plus some patches."
I ran and continue to run qmail without any patches.
The above quoted statements thus cannot be true.
But maybe "nobody" and "everybody" are figures of speech?