I'm reposting my email reply that did not make it to nanog (it made it fine
to ietf list though as did Tony's reply to my email that went to both sidr
and to nanog). I suspect nanog maybe using special filtering rules
[aka amavisd] that did not non-ascii characters in "To" field (that is the only thing I can think of that in how that post was different from others) - I can't think of a good reason to have this filtering rule though...