I saw this was discussed a month or two ago, but no conclusion seemed
to be reached.
I have qmail 1.03, and vpopmail 5.4 installed, and everything works
except for SMTP AUTH. I get segfaults or bad user errors, depending on
whether or not vchkpw is owned by root or by the vpopmail user.
Here's a transcript from a session where vchkpw was owned by vpopmail.
When it's owned by root, the last line changes to simply say the
220 domain.com ESMTP
250-AUTH LOGIN PLAIN
454 oops, problem with child and I can't auth (#4.3.0)