Hi Chris,
We have recently encountered the same behaviour and we also believe it to be an
issue on Microsofts end.
We have confirmed that if you alter the headers to remove the "Original"
component then the signatures will validate again (which is not something we
should need to do)
We'll be
My $DAYJOB has a service that does some email processing for customers
with Microsoft email, where MS gets a message, passes it to us with a
criteria based route, and then we pass it back to MS. We are setting up
ARC to meet MS's requirements, and I have found that MS is passing
messages to us
