Reclassification of Sender ID and SPF to Historic Status

This memo reclassifies RFC 4405, SMTP Service Extension for Indicating the Responsible Submitter of an E-Mail Message, RFC 4406, Sender ID: Authenticating E-Mail, RFC 4407, Purported Responsible Address in E-Mail Messages and RFC 4408, Sender Policy Framework (SPF) for Authorizing Use of Domains in E-Mail, Version 1 to Historic status. This memo also obsoletes RFC 4405, RFC 4406, RFC 4407, and RFC 4408.