April 25, 2005
Q: I keep getting a particular spam e-mail selling pills (with the) same name of the pills. I have gone into my message rules in Outlook Express and put a block to these words, but it doesn’t work. I can’t block the address or subject because it’s always different. But the message is always the same. Why can’t I get (the blocking) to work? — Lee
A: Unsolicited commercial email messages continue to mount in all of our inboxes, and just when it seems that we have a new way to filter them out, they come back!
There was a time not too long ago when word-based filtering was fairly effective. You could tell your e-mail program to delete or move any message that had certain words in the subject line or body of the message, and you no longer had to see them.
The problem with any spam filtering system, especially if it is effective or popular, is that it will be compromised. Remember, the bad guys can deconstruct the filtering systems and algorithms to figure out ways to work around them.
The spammers’ workaround for e-mail message rules is actually quite simple and well known in that subversive community.
Because all e-mail programs now support HTML (Hyper Text Markup Language — the programming language used to create Web sites), what you see with your eyes can be masked within the HTML to bypass your word based filtering attempts.
For instance, a recent spam message that I received had the following in the body of the message: VALIUM VIAGRA CIALIS. A word-based filter would not have seen it that way because the underlying code looks something like this (not in its entirety): VA </ TD>
The actual words are hidden in the code but appear like normal words to you because your e-mail program is translating the code into a usable string of text.
Message filtering is still useful for regular text messages and can be used in
reverse to possibly improve your e-mail life.
Instead of trying to filter out everything you don’t want, you may find it easier to filter out what you do want, if you don’t have a huge number of people that you truly want to hear from.
Try creating a message rule that looks at the sender’s address and moves all desired messages to a folder called "clean" (or whatever you choose) based on approved email addresses you list in the rule.
This does not eliminate the need to sift through the junk in your Inbox, but it does make getting to your known friends and family’s messages much easier.
As messages from new desired senders hit your Inbox, add them to the list in your message rule.
There are a plethora of methods for fighting spam, but they all have tradeoffs in either accuracy or the load that they create on users and mail systems.
In next week’s column, I will explain the pros and cons of many of the common spam filtering systems so you can decide what is best for you.