Anti-Spam filters…
Sent 6/4/2003
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Greetings,
After spending a ridiculous amount of time the past week or so on first the manual filters and then tweaking the automatic filters on the upgraded version of the mail server I have turned over the processing to the little robots inside the mail server. Imagine the amount of SPAM that you would get on your own and then multiple that by the 300+ accounts on the mail server. I was having to look through all that crap multiple times per day.
I am sure that there will be “False Positives”, meaning valid email that get’s flagged as SPAM, just as there will be SPAM that gets through – no system is fool-proof (the spammers will just be bigger fools). Should you get contacted by someone that this happens to please just send me their email address so that I can add their domain to the “white-list” and thereby allow mail from them to come through the firewall that is on the mail server. Or if there is an email list that you are subscribed to and suddenly you find that you are no longer getting mail from that address anymore forward one of the emails from that person or list to the address, admin@microworks.net and I will see about updating the “white-list” with that domain too.
How it works: The server first looks to verify that the sending server is who it says it is and that the account sending the mail is in fact valid on that server. If it fails those initial tests (it get’s five tries) the message is automatically deleted. If it passes those tests the message is then put through a Statistical word and phrase filter. If it fails at that level it is deleted too. The Statistical filter analyzes the email to determine a probability that the email is spam based on a number of criteria, such as the way the email is formatted, etc… If it has a determined probability of greater than 90% that it is SPAM the message gets deleted. If it survives the Statistical filter the message get’s run through a Phrase Filter looking for keywords. If it finds them the message will get deleted.
It is sad that Firewalls and roadblocks like this have to be erected but I am sure you realized that you probably got more junk email than real email. Not only does that impact your productivity but it impacts our productivity too in degraded performance of the servers and the connections having to bear this increasing load.