Yahoo antispam authentication RFC, GPL, freeware MTA, etc.

[davidh]

# Yahoo!'s DomainKeys Intellectual Property may be licensed under either of the following terms: Yahoo! DomainKeys Patent License Agreement
# GNU General Public License version 2.0 (and no other version).

In accordance with RFC2026, Yahoo! has also submitted the above license statement to the IETF as an IPR Disclosure. Have license feedback?
Reference Implementation
In addition to the Internet-Draft, Yahoo! has developed a reference implementation for DomainKeys that can be plugged into Message Transfer Agents (MTAs), such as qmail. A version of this software has been released and is available at http://domainkeys.sourceforge.net/. Sendmail has developed a DomainKey implementation for their popular MTA (both the commercial and freeware versions). In fact, Sendmail, Inc. has released an open source implementation of the Yahoo! DomainKeys specification for testing on the Internet and is actively seeking participants and feedback for this Pilot Program.

http://antispam.yahoo.com/domainkeys