SPAM == Junk Email
Junk email that comes in many forms. Since I have the pleasure of running my own MTA, I can personally block a great deal of spam before it ever infects my mail server inbox. However, most end users don't have that luxury (and if they did, they probably wouldn't know how).
Ken's Approach (experiments really)
First, don't use Exchange. Use some form of Unix or Linux (I use Debian because Redhat isn't free.) Use the Postfix MTA. Also, install mysql, but be sure to be firewalled.
I'm using greylisting recently. It seems to be working well, and it is interesting to watch the greylist database in mysql.
Greylist ideas (expanding on the idea)
This is just fun.... really cool.
- PERL? PHP on the command line just seems wierd to me. I'm adapting, however.
- "darklisting". Closer to black than grey. Darklisting would add a table to the database that stores all the IP addresses that failed the greylist test. Perhaps also add a counter that counts how many times they have failed the greylist test. The cleaner can easily do this. These would be in line for further research, blacklisting, or RBL reporting. Perhaps a web page published with the list of son-of-a-bitch IPs. It just makes sense to keep track of offending IP's, don't just forget about them.
- Web based administration tool. I've been working on a web based tool that lists the greylist for me, and allows me to click an IP address and easily click to blacklist or whitelist the IP. I'm just not so sure that web-based authentication is as secure as working on the command line. In my little network it isn't such a serious issue. At a bank, I suppose it might be a show-stopper. Using a web-server just seems to make sense since the greylisting is already in PHP.