User authentication question?

[Ishwar Rattan <rattan@cps.cmich.edu>]

The system is:
Linux pali 2.6.23.14-slh-smp-1 #1 SMP PREEMPT Mon Jan 14 23:28:40 CET 
2008 i686 GNU/Linux

I am trying to configure dovecot imap server. How can I  figure if the 
system is PAM for authentication or not?

Can it be configured to user /etc/shadow info to authenticate the users 
on the system? If so, what
will be the sample entry for /etc/shadow case in 
/etc/dovecot/dovecot.conf file?

-ishwar