=== postfix's master.cf ===

#
# DKIMproxy Area
#

#
# modify the default submission service to specify a content filter
# and restrict it to local clients and SASL authenticated clients only
#
submission  inet  n     -       n       -       -       smtpd
    -o smtpd_etrn_restrictions=reject
    -o content_filter=dksign:[::1]:10027
    -o receive_override_options=no_address_mappings
    -o smtpd_recipient_restrictions=permit_mynetworks,reject

#
# specify the location of the DKIM signing proxy
# Note: the smtp_discard_ehlo_keywords option requires a recent version of
# Postfix. Leave it off if your version does not support it.
#
dksign    unix  -       -       n       -       10      smtp
    -o smtp_send_xforward_command=yes
    -o smtp_discard_ehlo_keywords=8bitmime,starttls

#
# service for accepting messages FROM the DKIM signing proxy
#
[::1]:10028 inet  n  -      n       -       10      smtpd
    -o content_filter=
    -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks
    -o smtpd_helo_restrictions=
    -o smtpd_client_restrictions=
    -o smtpd_sender_restrictions=
    -o smtpd_recipient_restrictions=permit_mynetworks,reject
    -o mynetworks=[::1]/128
    -o smtpd_authorized_xforward_hosts=[::1]/128

# EOF

=== netstat & sockstat in FreeBSD 4.11-STABLE ===

pinus# netstat -anf inet6
Active Internet connections (including servers)
Proto Recv-Q Send-Q  Local Address          Foreign Address        (state)
tcp6       0      0  ::1.10028              *.*                    LISTEN
tcp6       0      0  *.587                  *.*                    LISTEN
tcp6       0      0  *.25                   *.*                    LISTEN
tcp6       0      0  ::1.10027              *.*                    LISTEN

pinus# sockstat -6
USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS         FOREIGN ADDRESS
root     master    5468   12 tcp6   *:25                  *:*
root     master    5468   71 tcp6   *:587                 *:*
root     master    5468   77 tcp6   ::1:10028             *:*
dkimprox perl      5420    4 tcp6   ::1:10027             *:*
dkimprox perl      5419    4 tcp6   ::1:10027             *:*
dkimprox perl      5418    4 tcp6   ::1:10027             *:*
dkimprox perl      5417    4 tcp6   ::1:10027             *:*
dkimprox perl      5416    4 tcp6   ::1:10027             *:*
dkimprox perl      5415    4 tcp6   ::1:10027             *:*


=== postfix's log ===

Feb  1 13:58:06 pinus postfix/master[5468]: daemon started -- version 2.4.5, configuration /usr/local/etc/postfix
Feb  1 14:01:28 pinus postfix/smtpd[5534]: connect from chrys.izb.knu.ac.kr[2001:470:1f05:5f8:3::1]
Feb  1 14:01:29 pinus postfix/smtpd[5534]: 3CD723E62: client=chrys.izb.knu.ac.kr[2001:470:1f05:5f8:3::1]
Feb  1 14:01:29 pinus postfix/cleanup[5537]: 3CD723E62: message-id=<49852CB4.6000109@izb.knu.ac.kr>
Feb  1 14:01:29 pinus postfix/smtpd[5534]: disconnect from chrys.izb.knu.ac.kr[2001:470:1f05:5f8:3::1]
Feb  1 14:01:29 pinus postfix/qmgr[5470]: 3CD723E62: from=<bh@izb.knu.ac.kr>, size=873, nrcpt=1 (queue active)
Feb  1 14:01:29 pinus postfix/smtp[5538]: 3CD723E62: to=<bhujuk@gmail.com>, relay=::1[::1]:10027, delay=0.4, delays=0.34/0.02/0.04/0, dsn=4.4.2, status=deferred (lost connection with ::1[::1] while receiving the initial server greeting)