Requirements for a DomainKeys Identified Mail (DKIM) Signing Practices Protocol

DomainKeys Identified Mail (DKIM) provides a cryptographic mechanism for domains to assert responsibility for the messages they handle. A related mechanism will allow an administrator to publish various statements about their DKIM signing practices. This document defines requirements for this mechanism, distinguishing between those that must be satisfied (MUST), and those that are highly desirable (SHOULD). This memo provides information for the Internet community.