My suggestion is to ask some implementers. If they think it made
implementing DKIM hard, or they see value to removing it, then do so.
The biggest problem with x= is that it mainly exists to support the
false belief that senders can tell recipients what to do.
If I sign a message with x= set to three years in the future, what's a
recipient supposed to do? How about three months? Three weeks?
Three days? Three minutes? I don't understand what is right thing
for a receiver to do with x= and I don't think anyone else does
either.
A reasonable verifier can completely ignore x= and still get the right
result in all non-silly cases, which tells me that x= should go.
R's,
John
PS: This is the same reason that l= should go.
_______________________________________________
NOTE WELL: This list operates according to
http://mipassoc.org/dkim/ietf-list-rules.html