Embodiments are directed towards detecting and reporting use by a domain of a message authentication mechanism, such as DomainKeys (DK), and/or DomainKeys Identified Mail (DKIM), and enabling subsequent blocking of messages based, in part, on its usage. When a message is received by an inbound message server, a message source is determined for the message. In one embodiment, the message source is a domain name associated with the sender of the message. Statistics are recorded about the message, including the message source, whether the message is suspect, includes a forged source identifier, employs DK/DKIM message authentication, and the like. The reports may ten be sent to various message sources to enable them to determine the extent of use of DK/DKIM message authentication, and to selectively block, re-direct, or forward the messages based, in part, on the use of DK/DKIM message authentication mechanism.