Domain Keys Identified Mail
charter-ietf-dkim-04-01

Domain Keys Identified Mail (DKIM, RFC 6376) defines a method for
using a digital signature to associate a domain identity with an email
message using an appropriate cryptographic authentication mechanism, and
to assure receiving domains that the message has not been altered since the
signature was created. Receiving systems can use this information as
part of their message-handling decision. This can help reduce spam,
phishing, and other unwanted or malicious email.

A DKIM-signed message can be re-posted, to additional recipients, in a
fashion that retains the original signature. With an author and a recipient
collaborating, this can "replay" the message, using the original signer's
reputation to propagate email with problematic content -- spam, phishing,
and the like.

Generally, the technical characteristics of this form of abuse match those of
legitimate mail, making its detection or prevention challenging. Timestamps
and carefully-tailored message signing conventions are appealing approaches
to replay mitigation. Each has significant limitations.

The DKIM working group will produce one or more technical specifications that
describe the abuse and propose replay-resistant mechanisms. The working group will
seek compatibility with DKIM's broad deployment.

Current proposals include the following drafts:

- draft-bradshaw-envelope-validation-extension-dkim
- draft-chuang-dkim-replay-problem
 - draft-chuang-replay-resistant-arc
 - draft-gondwana-email-mailpath
 - draft-kucherawy-dkim-anti-replay

The working group may adopt or ignore these as it sees fit.