The Spam Prevention Early Warning System (SPEWS) was an anonymous service that maintained a list of IP address ranges belonging to internet service providers (ISPs) that 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SPEWS is no longer active.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 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