Hardening your Mail Transfer Agent (MTA) and related services

TODO

SASL authentication via Dovecot

TODO

Preventing abuse of database backends

TODO

Privacy for Postfix

Cleaning headers for outgoing mail:

# /etc/postfix/extra/header_checks
/^Received: from 127.0.0.1/     IGNORE
/^User-Agent:/                  IGNORE
/^X-Mailer:/                    IGNORE
/^X-Originating-IP:/            IGNORE
/^X-Sanitizer:/                 IGNORE
/^X-Spam-Status:/               IGNORE
/^X-Spam-Level:/                IGNORE
/^X-MSMail-Priority:/           IGNORE
/^X-MimeOLE:/                   IGNORE

In your main.cf configuration file:

# The header_checks parameter specifies an optional table with patterns
# that each logical message header is matched against, including
# headers that span multiple physical lines.
# By default, these patterns also apply to MIME headers and to the
# headers of attached messages. With older Postfix versions, MIME and
# attached message headers were treated as body text.
# For details, see "man header_checks".

header_checks = regexp:/etc/postfix/extra/header_checks