Author Domain Signing Practises

In computing Author Domain Signing Practises (ADSP) is an optional part of the E-mail authentication scheme DKIM, formerly DomainKeys. Some ADSP details are still under discussion in the IETF working group DKIM.

Concepts

With ADSP domain owners can publish that all mails From their domain have a corresponding DKIM signature as defined in RFC 4871. The variant formerly known as a strong signing practise could state that other mails claiming to be From authors in the ADSP domain are discardable.

Instead of the From header, ADSP can also be used for publishing that all mails of the MAIL FROM, Sender, Resent-Sender and Resent-From headers have a corresponding DKIM signature.

Here From refers to the RFC 2822 e-mail header field From. The domains in 2822-From addresses are not necessarily the same as in the more elaborated Purported Responsible Address covered by Sender ID specified in RFC 4407.

The domain in a 2822-From address is also not necessarily the same as in the envelope sender address defined in RFC 2821, also known as SMTP MAIL FROM, envelope-From, 2821-From, or Return-Path, optionally protected by SPF specified in RFC 4408.

History

For some time ADSP was known as ASP Author Signing Practises, SSP Sender Signing Practises, and SSP Sender Signing Policy. It was never a part of SPF.

Eric Allman, the author of Sendmail, was the editor of the ADSP memo for the IETF DKIM Working Group.

External links

• IETF DKIM page with the current ADSP draft