Spam Slammers

摘要

While there are now many anti-spam techniques, two basic techniques, blacklists and content filtering, have proven to be reasonably effective. They're used―in one form or another, often in tandem―by almost every anti-spam product. Several third-party organizations maintain blacklists, which are lists of IP addresses or domain names known to be originators of spam. Businesses can decrease the amount of spam they receive by subscribing to blacklists, which are maintained by the greater community of Internet service providers, backbone providers, and other interested parties. Most anti-spam products let you choose which third-party blacklists you want to use, and will query the blacklists using a DNS query to the blacklist maintainer's Web site, or by using a locally cached version of the blacklist database. If the header of an E-mail message indicates that the message originated from a site on the blacklist, the E-mail is bounced, discarded, or flagged for more processing.