In https://wiki.dovecot.org/HowTo/Fail2Ban, for a current (I know for a fact in 2.2.36) I believe it should be filter = dovecot instead of filter = dovecot-pop3imap [root at mail ~]# ls -l /etc/fail2ban/filter.d/doveco* -rw-r--r-- 1 root root 1875 May 11 2017 /etc/fail2ban/filter.d/dovecot.conf [root at mail ~]#