SMTP Auth questions

Hi all,

I am about to engage the SMTP AUTH on my qmail server which lives since
2002.

I read :
- http://www.fehcom.de/qmail/smtpauth.html
- http://members.elysium.pl/brush/smtp-auth/server.html

I still have questions before doing anything.

I would like to know :
- what is the current RFC for SMTP Auth, 2554, 4954 or other ?
- Is there any patch which configure in the same time port 587 and the
auth mechanism ?
Most important :
- Could I use a separate database for user/password auth, other than the
/etc/passwd base ? Papers tell this is ok but patches I find only allow
/etc/passwd-shadow as far as I can see (qmail-smtpd-auth-058 for exemple)
- Or does someone use a plain text file to store all user/password and
with wich program (another kind of checkpassword).


Fanx much for any response