A NULL MX Resource Record for Domains that Accept No Mail

Document Type Replaced Internet-Draft (appsawg WG)
Authors John Levine  , Mark Delany 
Last updated 2014-01-30 (latest revision 2014-01-03)
Replaced by RFC 7505
Stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Expired & archived
pdf htmlized bibtex
Stream WG state Adopted by a WG
Document shepherd Dave Crocker
IESG IESG state Replaced by draft-ietf-appsawg-nullmx
Consensus Boilerplate Unknown
Telechat date
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


When the 5321.MailFrom domain in an e-mail message has a DNS MX Resource Record (RR), it is making an explicit statement that it is willing to accept email. However, when the domain has just a DNS A or AAAA RR, there mail clients cannot easily tell whether the domain accepts mail, as many hosts on the Internet advertise an A or AAAA RR regardless of whether they want to accept email. The NULL MX RR formalizes the existing mechanism by which a domain announces that it accepts no mail.


John Levine (standards@taugh.com)
Mark Delany (mx0dot@yahoo.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)