fyi;
Sendmail.com has announced that they are working with Yahoo on Yahoo's
DomainKeys system. (Note: There is some bad info going around that it
is Sendmail and MicroSoft.)
There aren't any technical details, but the announcement can be seen at:
https://www.sendmail.com/smi/news/pressrelease.jsp?eventOID=80351&localId=USA
-wayne