fail2ban/config/filter.d/postfix.conf

# Fail2Ban configuration file
#
# Author: Cyril Jaquier
#
#

[Definition]

# Option:  failregex
# Notes.:  regex to match the password failures messages in the logfile. The
#          host must be matched by a group named "host". The tag "<HOST>" can
#          be used for standard IP/hostname matching and is only an alias for
#          (?:::f{4,6}:)?(?P<host>[\w\-.^_]+)
# Values:  TEXT
#
failregex = reject: RCPT from (.*)\[<HOST>\]: 554
            reject: RCPT from (.*)\[<HOST>\]: 450 4\.7\.1 : Helo command rejected: Host not found; from=<> to=<> proto=ESMTP helo= *$

# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT
#
ignoreregex =