[Dovecot] Dovecot and file permissions

[Spectron International, Inc.]

I have some questions about some parameters in dovecot.conf, I have them
configured as this:

# User to use for the login process. The user must belong to a group where
# only it has access, it's used to control access for authentication process
# named sockets
login_user=postfix

# User to use for the process. Only shadow and pam authentication requires
# roots, so use something else if possible
auth_user=postfix

It seems to me that all files created and used by Dovecot as long as they
were created by the postfix user, they would be accesible. Right? My maildir
shows as this:

drw-------    6 postfix  postdrop       65 Jun 26 09:40 Maildir

so I guess postfix has full access to the maildir. Wouldn't setting
login_user and auth_user to postfix  let Dovecot access the Maildir? In the
logs I get permission errors, if I chmod to 777 it works ok. This is what I
get in the logs:

Jun 26 09:24:23 backup imap(f_rojas): opendir(/opt/mail/f_rojas/Maildir)
failed: Permission denied
Jun 26 09:24:31 backup imap(f_rojas):
stat(/opt/mail/f_rojas/Maildir/.Drafts) failed: Permission denied
Jun 26 09:24:31 backup imap(f_rojas): lstat(/opt/mail/f_rojas/Maildir/cur)
failed: Permission denied
Jun 26 09:24:31 backup imap(f_rojas): stat(/opt/mail/f_rojas/Maildir/.Sent
Items) failed: Permission denied
Jun 26 09:24:31 backup imap(f_rojas): lstat(/opt/mail/f_rojas/Maildir/cur)
failed: Permission denied
Jun 26 09:26:52 backup imap(f_rojas): lstat(/opt/mail/f_rojas/Maildir/cur)
failed: Permission denied
Jun 26 10:06:09 backup imap(f_rojas): lstat(/opt/mail/f_rojas/Maildir/cur)
failed: Permission denied
Jun 26 10:06:15 backup imap(f_rojas): opendir(/opt/mail/f_rojas/Maildir)
failed: Permission denied
Jun 26 10:08:38 backup imap(f_rojas): opendir(/opt/mail/f_rojas/Maildir)
failed: Permission denied
Jun 26 10:13:03 backup imap(f_rojas): stat(/opt/mail/f_rojas/Maildir/.Sent
Items) failed: Permission denied

Faw