Centos6 (2.x)

/etc/dovecot/dovecot.conf

dovecot.conf

#use minimal protocols
#protocols = imap pop3 lmtp
protocols = imap pop3

#only ipv4 :: mean all ipv6 ip's
#listen = *, ::
listen = *

/etc/dovecot/conf.d .. 10-auth.conf

10-auth.conf

# dovecot 1.x default is "no"
disable_plaintext_auth = no

# use username h-imaoka@example.jp  = <h-imaoka>
auth_username_format = %n

#keep it
auth_mechanisms = plain

auth-system.conf.ext

passdb {
  driver = pam
  # [session=yes] [setcred=yes] [failure_show_msg=yes] [max_requests=<n>]
  # [cache_key=<key>] [<service name>]
  #args = dovecot
  args = login
}

args = login means /etc/pam.d/login

10-mail.conf

# There are a few special variables you can use, eg.:
#
#   %u - username
#   %n - user part in user@domain, same as %u if there's no domain
#   %d - domain part in user@domain, empty if there's no domain
#   %h - home directory
#
# See doc/wiki/Variables.txt for full list. Some examples:
#
#   mail_location = maildir:~/Maildir
#   mail_location = mbox:~/mail:INBOX=/var/mail/%u
#   mail_location = mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%n

mail_location = mbox:~/mail:INBOX=/var/mail/%u

mail_access_groups = mail

10-ssl.conf (optional)

10-ssl.conf

# SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
ssl = no

trouble shooting

can not start daemon (protocol error)

set listen port = * (ipv4 only)

pam auth failure (locked account)

use login pam auth.

clear failure count
pam_tally2 --user=<user name> --reset
corrent failure count
pam_tally2 --user=<user name>

login succeeded but disconnected from server

confirm mail_location setting

dovecot notes