Is there a mailing list discussing this draft?
The null mx record structured in this manner:
* IN MX 0 .
may inundate root servers with lookups for addresses to ".". This was
the reason the dot target was avoided in the CSV-CSA draft. This has
been a problem, even where code, specifically written to handle SRV
records, should recognize a "." target as invalid. The nullmx draft
uses this name to accept bounces and invalid domains for boat-loads of
email, where code may not provide special handling for this "." target
name.
To avoid a concentration of address lookups to ".", perhaps:
* IN MX 0 accepts-no-mail
accepts-no-mail IN AAAA 0:0:0:0:0:0:0:0
accepts-no-mail IN A 0.0.0.0
A client, that does not understand this syntax, may attempt a session
with an invalid destination address. See RFC1700, RFC3513. Such packets
should be refused at the routers. Either the target name or address
could be given special significance.
-Doug