OT: AUTH=LOGIN documentation, anyone?

[Kris Kelley]

Forgive me for an off topic post, but I'm hoping somebody here can point me
in the right direction.

I'm looking for documentation that details how the ESMTP AUTH=LOGIN
mechanism works.  There doesn't seem to be an RFC for it, and I haven't had
any luck finding other documentation.  The AUTH=LOGIN mechanism is used by a
couple of qmail patches to provide SMTP relay authentication, and a coworker
of mine needs to know how it works so he can write an email client for it.
Thanks!

---Kris Kelley