DKIM Originating Signing Policy (DOSP)
DOSP (DKIM Originator's Signing Policy) is a DNS-based mechanism for associating domain-names and asserting separate DKIM related policies for all originating header fields and parameters found in DKIM related messages. DOSP can associate an email-address with a list of signing domains, and a signing domain with a list of SMTP Clients. DOSP also provides a means to assert whether signatures are always initial provided, whether there was an effort to protect these signatures, their role related to offering assurances, such as when an identity referencing the DOSP policy is assured to be valid.