SeeYouLater's purpose is to fetch a list of IPs of known spammers and to ban them by putting them in /etc/hosts.deny. /etc/hosts.deny is usually read by xinetd or daemons using tcpwrapper. The software is composed of: the feeder, that looks at SMTP daemon logs for the string ++BAN:IP++ and feeds the database accordindly; and the butcher, that looks at the database and updates /etc/hosts.deny. You may want to run the butcher on a system that has no access to the SMTP logfiles, but you can install both packages on the same system. It has been written to run with Exim.