Spam Prevention Early Warning System

The Spam Prevention Early Warning System (SPEWS) was an anonymous service which maintained a list of IP address ranges belonging to Internet service providers (ISPs) which host spammers and show little action to prevent their abuse of other networks' resources. It could be used by Internet sites as an additional source of information about the senders of unsolicited bulk email, better known as spam.

SPEWS is no longer active. A successor, the Anonymous Postmaster Early Warning System (APEWS), appeared in January 2007.

SPEWS itself published a large text file containing its listings, and operated a database where web users could query the reasons for a listing. Users of SPEWS could access these data via DNS for use by software for DNSBL anti-spam techniques.

For instance, many mail sites used the SPEWS data provided at spews.relays.osirusoft.com. All DNSBLs hosted by Osirusoft were shut down on August 27, 2003 after several weeks of denial of service attacks. A number of other mirrors existed based on the SPEWS data, which remained accessible to the public. SORBS, for example, provided a mirror of SPEWS data until early 2007.

There was a certain degree of controversy regarding SPEWS' anonymity and its methods. By remaining anonymous, the SPEWS admins presumably wanted to avoid harassment and lawsuits of the sort which have hampered other anti-spam services such as the MAPS RBL and ORBS.

Some ISP clients whose providers were listed on SPEWS took umbrage that their own IP addresses were associated with spamming, and that their mail might be blocked by users of the SPEWS data; often they did not understand that it was their provider that was listed. Sometimes, the only solution was to leave the blacklisted provider, as SPEWS was not willing to cut holes in a listing for a clean user in an otherwise dirty IP block. There was no way for either the customer or the provider to contact SPEWS, and SPEWS claimed that the listings would be removed only when the associated abuse stopped.

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