[Dovecot] authentication configuration

[Tom Allison]

I've included the non-defaulted bits of my dovecot.conf file at the 
bottom of this email.

As I understand my set-up it's using unix authentication methods 
(/etc/passwd via pam?).

Considering disable_plaintext_auth and auth_mechanisms, what exactly is 
being passed?  I was hoping to get
auth_mechanism = digest-md5
but that's not working out very well right now.  It seems I can only do 
plaintext authentication.

I got stuck on the userdb/auth_passdb settings.  Can someone give me an 
example of how to configure for md5-digest authentication?

My current guess is:
disable_plaintext_auth = yes
auth = digest-md5
auth_mechanism = digest_md5
auth_passdb = /etc/mydigestfile

How would I set this for pgsql?  auth_passdb = /etc/dovecot-pgsql.conf


###  non-default config settings.
protocols =  imap imaps
disable_plaintext_auth = yes
login = imap
login_max_processes_count = 16
login = pop3
max_mail_processes = 512
default_mail_env = maildir:~/Maildir
mailbox_check_interval = 1
auth = default
auth_mechanisms = plain
auth_passdb = pam
auth_user = root