Anonymous Postmaster Early Warning System
The Anonymous Postmaster Early Warning System (APEWS) is an anonymous service that maintains a list of IP address ranges (L2 list) and domain names (L1 list) belonging to internet service providers (ISPs) that the anonymous maintainers claim to be hosting spammers and failing to prevent their abuse of other networks' resources.
According to the only public forum communication ever released by APEWS, the service was founded by people who observed that the Spam Prevention Early Warning System (SPEWS) was inactive, no longer maintained, and possibly dead. Unlike SPEWS, APEWS operates two blacklists: a Right-Hand Side Blacklist (RHSBL) that lists domains as well as a Domain Name System Blacklist (DNSBL) that lists IP address ranges.[1]
Discussion
There is an ongoing discussion of the validity and utility of the APEWS list. The widely-used resource at DNSStuff.com[2] recommends against using the APEWS list. APEWS lists at present approximately 40 percent of routable IPV4 address space, including, for instance, 12.0.0.0/9, rendering it useless in a production environment for simple blocking (accept/reject). The maintainers provide links to two popular USENET newsgroups in lieu of an actual removal queue, and this has given rise to displeasure among users of those newsgroups. This and APEWS's lack of any coherent policy governing listings militate against its being taken seriously by the anti-spam community.
Since the APEWS list used in an actual production environment seems to be very limited, it is not known how email users are being made aware of listings. To date, there is not a single verified public report of email being rejected as a result of a listing in APEWS.