> Fallback to A should be removed sure sounds like a plan.
great idea. it will only break mail to 42% of the internet.
Since there is no fallback to AAAA, in a few years it will
break very little as most of the internet will have IPv6
MTA's (and hence MX's) for their mail domains.
MX fallback to A should have had a sunset time added to it
when it was originally proposed. It is, after all, only a
transition strategy. We can still add a sunset clause.
MTA's would lookup their own MX records for the mail domains
they are configured as final delivery agents for and if not
found log that there are missing MX records.