[Dovecot] separate passdb for imap and pop3

[Scott Alter]

> But how can I configure dovecot to use the 'auth imap' for imap
> authentications, and use 'auth pop3' for pop3 authentications. With the
> above setup dovecot always try to use the last one (auth imap).
> Any help would be appreciated!

You do not need to have separate auth sections to do what you want.  
Simply use
variables to specify the service name in the path of the password file:

auth default {
mechanisms = plain digest-md5
passdb passwd-file {
   args = /etc/dovecot_%Ls.passwd
}
userdb passwd-file {
   args = /etc/dovecot_%Ls.passwd
}
user = _dv_auth
}

%s should give you POP3 or IMAP, and the L modifier should make it 
lowercase. This is documented on the Variables page of the wiki.

Scott