In 2006, two experiments were started for email authentication: Sender Policy Framework (SPF, RFC 4408) and Sender ID (RFC 4406, supported by RFCs 4405 and 4407). After eight years of experimental data (RFC 6686), it was clear that SPF remained in widespread use while Sender ID did not. RFC 7208 moved SPF from Experimental status to Proposed Standard. This document acknowledges that Sender ID did not pass its experiment, and changes the status of RFCs 4405, 4406, and 4407 to Historic.