[Dovecot] What auth ?

[Spyros Tsiolis]

Hello people,

First of all a Happy New Year and best wishes to you all.

I've managed to setup dovecot v1.2.9 on a CentOS 5.4
system and I am now, trying to make it auth.

I would prefer virtual users and only want to make the IMAP/
IMAPS part work. I don't need POP3 or anything else. The rest
will be handled by another SMTP/POP3 application.

Now, I almost managed to make dovecot auth a virtual user with
his password. However, when it seems it has passed the auth
stage (either via IMAP _or_ IMAPS), the command line kicks me
out.

Here's roughly what I did :

1. Created /etc/dovecot/users and /etc/dovecot/passwd
2. filled in a couple of usernames/passwords encrypted in MD5 format
3. Ran dovecot from command line (service dovecot start [after I
   created the service ofcourse])
4. telneted to localhost via port 143 or 993 (with the help of openssl:
   "openssl s_client -connect the.system.name:993")
5. typed : . login username at fqdn <password>

Something worth noticing for step "5". If I do this logging-in with the
"user at fqdn" format, the systems kicks me out. I, then, check the latest
on "/var/log/dovecot/errors" to find that the system does not complain
about the auth.
If I do the same logging-in but instead use "user at localhost" (and not
the fqdn), the system fails the authentication stage and does _not_
drop me into the shell. Go figure !!

Anyway. My question, in essence, is this; 
Which type of auth should I use ?

The manuals (that i've been sinking my head for the last couple of weeks)
suggest I should use PAM. PAM, I cannot understand. At the moment, I _think_
I am using MD5. Any pointers here ? I've been reading the /doc/wiki
directory for quite some time until it made no sense to me anymore
(too much info makes me loose perspective).

Any help would be greatly appreciated.

TIA,

spyros