Viktor Dukhovni: > > In the RFC editor queue as of 2014-08-29: > > https://datatracker.ietf.org/doc/draft-ietf-appsawg-nullmx/
Hmm. This text says:
When a submission or SMTP relay server rejects an envelope recipient
due to a domain's null MX record, it SHOULD use a 521 reply
code [...]
Both 221 and 421 are sent at the end of an SMTP session. Postfix
uses 521 for the same purpose: is is like 421 except that the client
should not retry.
Maybe the draft can be modified.
Wietse
