%% You should probably cite rfc7505 instead of this I-D.
@techreport{ietf-appsawg-nullmx-02,
	number =	{draft-ietf-appsawg-nullmx-02},
	type =		{Internet-Draft},
	institution =	{Internet Engineering Task Force},
	publisher =	{Internet Engineering Task Force},
	note =		{Work in Progress},
	url =		{https://datatracker.ietf.org/doc/html/draft-ietf-appsawg-nullmx-02},
        author =	{John R. Levine and Mark Delany},
	title =		{{A NULL MX Resource Record for Domains that Accept No Mail}},
	pagetotal =	6,
	year =		,
	month =		,
	day =		,
	abstract =	{Internet mail determines the address of a receiving server through the DNS, first by looking for an MX record and then by looking for an A/AAAA record as a fallback. Unfortunately this means that the A/ AAAA record is taken to be mail server address even when that address does not accept mail. The NULL MX RR formalizes the existing mechanism by which a domain announces that it accepts no mail, which permits significant operational efficiencies.},
}