I thought this trademark issue was resolved at IETF-60. According to
Harry, the Microsoft lawyers investigated it and, unlike terms like
"windows", "word", and "access", they determined that "SenderID" was
generic and could not be trademarked.
Since the USPTO shows two live registrations (from the same company)
for the term SENDERID, I can't say that I'm too reassured by that
legal analysis. I can tell you from experience that if the USPTO
thinks a term is too generic, they won't accept a registration for it.
In the unlikely event that MARID recommends Microsoft's Sender-ID for
standardization in spite of its technical and patent problems, I agree
that it's no big deal at this stage to pick a different name.