fail2ban/config/filter.d/courier-smtp.conf

# Fail2Ban filter to block relay attempts though a Courier smtp server
#
#

[INCLUDES]

# Read common prefixes. If any customizations available -- read them from
# common.local
before = common.conf

[Definition]

_daemon = courieresmtpd

prefregex = ^%(__prefix_line)serror,relay=<HOST>,(?:port=\d+,)?<F-CONTENT>.+</F-CONTENT>$

failregex = ^[^:]*: 550 User (<.*> )?unknown\.?$
            ^msg="535 Authentication failed\.",cmd:( AUTH \S+)?( [0-9a-zA-Z\+/=]+)?(?: \S+)$

ignoreregex = 

# Author: Cyril Jaquier