It appears that Matus UHLAR - fantomas via mailop <uh...@fantomas.sk> said: >I'm sure we could reject many mail coming from hosts without MX record and >without running MTA on port 25, thus from undeliverable senders.
That would reject all mail from Gmail and every other large provider I know. Seems a bit extreme. It'd even reject mail from my tiny system since the inbound and outbound MTAs are on different IPs and neither has the name of the domain I use for mail. >Nowadays, we can mark domains that don't send mail using Null MX (rfc 7505). >But this needs explicit record to say "this domain does not send/receive >e-mail" > >Requiring MX to explicitly state "this domain does send/receive mail" would >clean up field a bit. It would, but fallback to A has been part of SMTP since RFC 974 in 1986 and it's not going away now. RFC 974 also descrived the WKS (Well Known Services) record that a domain could publish to say which services it supports, but that never worked. We invented null MX several decades later as a simpler alternative which does actually work if you use it. R's, John _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
