Analysis of information sources in references of the Wikipedia article "DomainKeys Identified Mail" in English language version.
DKIM was produced by an industry consortium in 2004. It merged and enhanced DomainKeys, from Yahoo! and Identified Internet Mail, from Cisco.
The DMARC standard states in Section 6.7, "Policy Enforcement Considerations," that if a DMARC policy is discovered the receiver must disregard policies advertised through other means such as SPF or ADSP.
Receivers who successfully verify a signature can use information about the signer as part of a program to limit spam, spoofing, phishing, or other undesirable behaviors. DKIM does not, itself, prescribe any specific actions by the recipient; rather, it is an enabling technology for services that do.
Verifying the signature asserts that the hashed content has not changed since it was signed and asserts nothing else about "protecting" the end-to-end integrity of the message.
The From header field MUST be signed (that is, included in the "h=" tag of the resulting DKIM-Signature header field).
Receivers who successfully verify a signature can use information about the signer as part of a program to limit spam, spoofing, phishing, or other undesirable behaviors. DKIM does not, itself, prescribe any specific actions by the recipient; rather, it is an enabling technology for services that do.
Verifying the signature asserts that the hashed content has not changed since it was signed and asserts nothing else about "protecting" the end-to-end integrity of the message.
The From header field MUST be signed (that is, included in the "h=" tag of the resulting DKIM-Signature header field).
DKIM WG opted for canonical form simplicity over a canonical form that's robust in the face of encoding changes. It was their engineering choice to make and they made it.
RFC 6376 has been elevated to Internet Standard.
The reference to the GPL looks to me like it only covers the old Sourceforge DK library, which I don't think anyone uses any more. The patent, which is what's important, is covered by a separate license that Yahoo wrote.
Yahoo! DomainKeys Patent License Agreement v1.2
Your policy can be strict or relaxed. For example, eBay and PayPal publish a policy requiring all of their mail to be authenticated in order to appear in someone's inbox. In accordance with their policy, Google rejects all messages from eBay or PayPal that aren't authenticated.
The reference to the GPL looks to me like it only covers the old Sourceforge DK library, which I don't think anyone uses any more. The patent, which is what's important, is covered by a separate license that Yahoo wrote.
