PAM MySQL / IMAP / Postfix - plaintext username cannot connect to pwcheck server

[info-cyrus at oliverpeek.com]

I am more than likely at fault, but I installed Cyrus IMAP, Postfix, and
used PAM MySQL for cleartext authentication and got the following error:

plaintext username cannot connect to pwcheck server

I found out that the PAM service couldn't connect to my database locally
because of a permission problem with the mysqld.sock unix socket.  The
postfix program had a problem with authentication as well because most of
the services for postfix were chroot'd and couldn't access the socket
either.  I had been looking for the problem for a long time, because I
never saw an error in my MySQL logs that seemed to correspond to the
postfix and IMAP authentication problems (mainly because I had two
machines, one for Postfix and one for Cyrus, when I combined both services
on the same machine, I saw the errors for Postfix, and fixed those
problems, and it fixed the Cyrus problems obviously).

This is not a bug or fault on the programmers end, this is simply an
overlooked solution for my problem.  I always thought there was something
wrong with pwcheck, when in fact, it was really the permissions of the
program doing the MySQL lookup for the pwcheck server which uses PAM. 
More than likely setting the pwcheck_pam to the mysql gid would do the
trick, but I haven't tried that yet.

This post is mostly an attempt to keep someone else from the same kind of
run around I made.  Setting up IMAP, Postfix, and PAM was a **breeze**
after I realized this problem.

Hope this helps someone out there doing multiple Google searches,
Oliver Peek