[ietf-dkim] Issue 1547: MX Record publishing mandate to reduce DNS overhead for SSP Discovery and to detect fraudulent messages

[Stephen Farrell]

Issue description: https://rt.psg.com/Ticket/Display.html?id=1547

I didn't see any consensus to mandate the use of MX and the current
text in ssp-04 seems to me to represent consensus.

Barring a significant number of calls to mandate MX, I'll ask Eliot
to close this on July 11th.

S.