AFAIR yahoo only looks for proper SPF records and then looks at content so far. My users interact with them all the time.
Out of curiosity: What happens if you don't have SPF records?
Ralph
Initially when I had to deal with sending to yahoo I would get a mix of mail dumping into the receivers spam box to downright rejections. Then it moved completely to rejections. I have exec's that send mail to all the big providers, usually to lawyers and lobbyists that are either too clueless or too cheap to have a better mail system. Aol and yahoo at the time just wanted SPF records and reverse DNS that resolves.
Been reading about this stuff for hours. I gotta say that spf might be the thing to try first. It does not prove who you are, but it is supposed to make the big mail companies feel warm and fuzzy to know you are trying to prove you 'are you'.
SO I will do that first (especially since it does not require any installation stuff)
On a side note...just got the RHEL annoucement. Huge kernel patch coming...woof.