MAPS maintains a huge database of IP addresses that have been identified with generating spam. MAPS is always fair and eager to work with network administrators to resolve any misidentified listings.

The spam listings include real-time black hole listings (RBL), Dynamic User listings, Relay Spam Stopper listings, Open Proxy Stopper listings, and Non-Confirmed Mail List listings. When an email is refused by MAPS, the ISP network administrator of the originating email must contact MAPS to investigate the refusal, and if a valid, non-spamming ISP, then take steps to have the address removed from MAPS blacklist.