"The OpenBSD project produces a FREE, multi-platform 4.4BSD-based UNIX-like operating system."

You can't really divorce UNIX from C.

The only other language option for an smtpd server in OpenBSD base would have been Perl, and I bet people would complain about that just the same.

And perhaps we wouldn't be able to review it properly if it was written in Perl. Perhaps Marc Espie could. But OpenBSD has plenty of people on the team who are well trained at auditing C.

I'll be doing my part and read some smtpd code during an 8h train ride tomorrow. I already read one file and found one bug in it and told gilles about it. That's how this works. Changing the language won't magically fix anything.