a system for denying or allowing delivery of an incoming electronic mail message that indicates a source e - mail server , source domain , and an addressee for the message . a central e - mail server registry database stores information for all e - mail servers authorized to send e - mail messages over the internet . each e - mail recipient can specify characteristics of domains that are authorized to send e - mail messages to the recipient . when an incoming e - mail message arrives at the recipient &# 39 ; s e - mail server , the server accesses the registry database to determine whether the source e - mail server and / or domain are registered , and if so , whether the registration in good standing , and whether the source domain possesses the specified characteristics . if these conditions are not met , delivery of the e - mail is denied . registered e - mail servers can download specified server information from the central registry and store it in a local registry . when incoming messages arrive at the server , the local registry is checked first , if unsuccessful , the central registry is checked .