Unwanted commercial emails are an annoying problem. Whenever we follow a link for merchandise and provide our email address, we encourage more unsolicited email. Sending forwarded email messages with a list of recipients also provides spammers with valid email addresses.
Apple Computer provides an email program called Mail for its Macintosh computers running the Mac OS X operating system. This email program has an effective junk mail filter to flag and remove unwanted messages.
The nature of spam is constantly evolving. Using filters that evaluate messages based on a list of keywords, patterns or rules becomes less effective as time goes on. Mail uses a statistical filter known as Adaptive Latent Semantic Analysis (LSA). It identifies spam-like words in messages based on their similarity in meaning to text that you have already identified as spam. Take for example the word “enlargement”. The junk mail filter examines the context of the word. Photographic enlargement is okay, but enlargement of any body part flags the message as junk. The meaning of the word is compared to prior junk email messages.
Mail’s Junk Mail filter has two modes: Training and Automatic. It can also be disabled entirely, so maybe there are three modes. In both the Training and Automatic mode the junk mail filter learns that a message is spam when you mark the message as Junk. This is done either by clicking the Junk button in the toolbar or by executing the command Mark as Junk Mail under the Message menu. This junk message will be used in evaluating new email messages.
This statistical filter will increase its accuracy in recognizing junk as long as you remember to mark these messages as junk. If you just delete these messages, it will increase the probability that similar messages will arrive in your mailbox.
The difference between the Training mode and the Automatic mode is that Mail simply gives an email message a brown color in the list of messages in your inbox in the Training mode. In the Automatic mode Mail makes a new mailbox called Junk. Messages that the filter sees as junk are placed in the Junk mailbox. Check the Junk mailbox from time to time. If Mail should incorrectly mark a legitimate message as junk, always mark such messages as Not Junk. Either click the Not Junk button in the toolbar or choose Mark As Not Junk under the Message menu.
Mail’s junk mail filter can be set to delete messages that it marks as junk. Remember that you must be very confident that there are no pieces of real mail getting mixed up in your junk mail before using this option. Although Mail’s junk mail filter learns from your past history, no system is perfect. Properly trained, Mail’s junk mail filter will identify most unwanted email.
Steve Hafenbredl
June 2004