After do-release-upgrade from Ubuntu 20 to Ubuntu 22 LFD was no longer blocking auth failures on imap and pop
First thing to check was LOGS settings in /etc/csf/csf.conf
Before do-release-upgrade syslog WAS /var/log/maillog
After do-release-upgrade syslog IS /var/log/mail.log
FIX : Edit /etc/csf/csf.conf
FROM:
POP3D_LOG = “/var/log/maillog”
IMAPD_LOG = “/var/log/maillog”
TO:
POP3D_LOG = “/var/log/mail.log”
IMAPD_LOG = “/var/log/mail.log”