[ietf-dkim] over-the-wire (in)compatibility between pre-IETF DKIM and (eventual) IETF DKIM

[Dave Crocker]

> I would be surprised though if the result for the signature construct
> (which may be a bit of a special case here) didn't have the "best"
> security option as the MUST-implement, even if it has the legacy
> signature construct as a MAY-emit. But we'll see when we get there...

Just to be obsessively careful, here:  Having one choice as a MUST and 
another as a MAY would seem to be mutually exclusive, if only one choice 
is allowed. 

Hence the implication of your expectation is that all recipients will be 
required to support multiple signatures...

d/