i got rid of those with fail2ban.
simply copy jail.conf to jail.local
cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local
and if you want you can enable [couriersmtp]
and if you need
i didnt create custom filter and stuff ... used default values and it works.
set retry to 3 times and you can set seconds as much as you want.
Used Ubuntu 8.04 and after last update I hope fail2ban will work after restart and if not after restart of server:
apt-get purge fail2ban
apt-get install fail2ban
to confirm that it is running:
no need to edit jail.local since file will not be deleted on uninstall.