%% You should probably cite draft-ietf-appsawg-nullmx instead of this I-D. @techreport{delany-nullmx-02, number = {draft-delany-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/draft-delany-nullmx/02/}, author = {John R. Levine and Mark Delany}, title = {{A NULL MX Resource Record for Domains that Accept No Mail}}, pagetotal = 5, year = 2014, month = jan, day = 3, abstract = {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.}, }