First off, let me say that I'm not into MS bashing. Secondly IANAL.
I did take the time to read the published patent applications several
times. I then went back to archives of (for example) the DRUMS list
and other earlier attempts to deal with spam and relaying issues. I
have a feeling (especially because folks from MS participated in some
of the efforts) that there is enough prior art /published information
that it would be rather straight forward to show that many of the
claims in the patent applications should not be granted. There's some
interesting stuff in earlier RFCs,Drafts and BIS if you do a little
digging.
There are some interesting discussions regarding envelope mailfrom
(specifically when RFC821 ans RFC822 were being created that would
indicate to me that MS would be hard pressed to claim they "invented"
this check. The specific context of some of the threads was with
regard to gateways from non-TCP systems/networks.
Instead of ranting about MS the evil empire or stopping the granting
of software patents, if you are truly serious about this issue then
folks will make an effort similar to what was done with SCO and their
intellectual property claims regarding UNIX and code.
As usual, just my 2 cents.
Mike