Fraud. In survey after survey, the overwhelming majority of Internet users dislike receiving spam. In response to such strong consumer opinion, many ISPs have taken a variety of costly steps to reduce the volume of spam transmitted through their systems, including the buildup of extra capacity to accommodate the demands of filtering and storing what represents, according to America Online, nearly 30 percent of its daily mail traffic. Knowing that ISPs have taken those measures, senders of junk e-mail use tricks to disguise the origin of their messages. One of the most common is to relay their messages off the mail server of a third party. This tactic doubles the damages, because now both the receiving system and the innocent relay system are flooded with junk e-mail. For mail that gets through, many times the flood of complaints goes back to the innocent site because that site was made to look like the origin of the spam. Another common trick is to forge the headers of messages, making it appear as though the message originated elsewhere and again providing a convenient target upon which the anger of recipients and the flood of complaints will land.