Install & Setup

Install

apt install opendmarc

# R8

yum install opendmarc    # epel

Config

/etc/opendmarc.conf

# "Authentication-Results:" header field
AuthservID OpenDMARC

# tells OpenDMARC to trust authentication result with mail.yourdomain.com
TrustedAuthservIDs mail.yourdomain.com

# By default, OpenDMARC won’t reject emails
RejectFailures true

# ignore SMTP clients that are successfully authenticated via SMTP AUTH.
IgnoreAuthenticatedClients true

# if an incoming email doesn’t have From: header or date: header, it will be rejected.
RequiredHeaders true

# This will make OpenDMARC perform a fallback SPF check itself when it can find no SPF results in the message header.
SPFSelfValidate true

# mkdir -p /var/spool/postfix/opendmarc
# chown opendmarc:opendmarc /var/spool/postfix/opendmarc -R
# chmod 750 /var/spool/postfix/opendmarc/ -R
# adduser postfix opendmarc
Socket local:/var/spool/postfix/opendmarc/opendmarc.sock

systemctl enable opendmarc --now

postfix config

main.cf

milter_default_action = accept
milter_protocol = 6
smtpd_milters = local:opendkim/opendkim.sock
non_smtpd_milters = $smtpd_milters

# 當使用 opendkim 時

smtpd_milters = local:opendkim/opendkim.sock,local:opendmarc/opendmarc.sock