The action that a spammer tries to achieve from a recipient is key to effective filtering.
What are these actions?
The simplest action is to follow a URL that takes the recipient to a web page. Just as simple, is to reply to the message. Not quite as simple, is to call a phone number. Calling the phone number typically connects you to an answering machine that asks you to leave a number where you may be reached. The spammer calls you back. The least likely action is to send a response by mail. Using the postal system is also unlikely for another reason: because fraud conducted via U.S. mail is a serious offense.
Posted by Doug Sauder at January 11, 2003 01:02 PM