1. […]

auth default {
# Space separated list of wanted authentication mechanisms:
# plain login digest-md5 cram-md5 ntlm rpa apop anonymous gssapi
mechanisms = plain login

1. […]
   1. It's possible to export the authentication interface to other programs:

socket listen {
#master {
# Master socket is typically used to give Dovecot's local delivery
# agent access to userdb so it can find mailbox locations. It can
# however also be used to disturb regular user authentications.
# WARNING: Giving untrusted users access to master socket may be a
# security risk, don't give too wide permissions to it!
#path = /var/run/dovecot/auth-master
#mode = 0600
# Default user/group is the one who started dovecot-auth (root)
#user =
#group =
#}
client {
# The client socket is generally safe to export to everyone. Typical use
# is to export it to your SMTP server so it can do SMTP AUTH lookups
# using it.
path = /var/spool/postfix/private/auth
mode = 0660
user = postfix
group = postfix
}
}

1. […]

root@server:/# /etc/init.d/dovecot restart
* Restarting IMAP/POP3 mail server dovecot Error: Error in configuration file /etc/dovecot/dovecot.conf line 1062: Unknown setting: user
Fatal: Invalid configuration in /etc/dovecot/dovecot.conf
[fail]

Já comentei esta linha, alterei para "user = server" ms dá-me os seguintes erros.

Error: Error in configuration file /etc/dovecot/dovecot.conf line 1081: Unknown section type (section changed in /etc/dovecot/dovecot.conf at line 1009)
Fatal: Invalid configuration in /etc/dovecot/dovecot.conf

O seu post sobre postfix Dovecot e Sasl foi muito útil para o meu trabalho e caso você tenha interesse em IPv6, eu poderia lhe ajudar.

Obrigado,
Robson