Ways to deal with Junk Mail (1 of 2)
Who hasn’t ever seen junk mail? From the offers for prescription drugs to offers for who knows what. Some mail programs give you a way to filter out different senders, but the senders of junk mail are always changing (like viruses.) So what other tools are there?
The reason there are two parts to this discussion is there are two approaches to catching junkmail. One is a server side solution. So if you have the ability to install software on your mailserver this first approach might be what you’re looking for. This applies if you have an in-house mailserver, or if you have a webhost who acts as the mailserver for your company or small-business or even your personal account.
Spamassassin is a GREAT open source spam filtering approach. The concept is fairly simple. Using a large set of tests messages are given a score for how “spammy” it is. The higher the number the more “spammy” So, for instance if the test is for the word cialis and any variations on spelling it might get several points added to the “spammines” The user then sets what threshold to set for determining mail to be spam and the subject can be rewritten to include ***SPAM***, or it can be configured to be more subtle (just adding a header tag like X-Spam: Yes Extremely spammy messages CAN be deleted automatically. I usually reserve that only for the SEVERELY high numbers. Additionally there are other test plugins that can be added and some scores can be customized. It gets better though. As it collects good and bad messages it starts it’s own database of what good messages and bad messages look like. When it has enough data to run with it starts using that as a further test.
Once a message is tagged on the server though it’s very easy to setup a junk folder in most any email program and then set up a “message rule” or “filter” to sort anything with ***SPAM*** into the junk folder.
Now most of the tests add to the spam rating, but some might subtract from it. So, one approach to whitelisting is to set up spamassassin to give say every address from averyjparker.com -15 points, or subtract 15 points from a message from that domain. All of the accounts that I deal with have spamassassin as an option and it is designed to be installed on a mailserver. It is free for linux servers, Windows servers have to find a pay product that utilizes spamassassin as far as I know.