1. Summary
Tony Hansen is the Document Shepherd. Barry Leiba is the responsible
Area Director. This document is an individual submission.
This memo defines two Simple Mail Transfer Protocol (SMTP) reply
code, 521 and 556. The 521 code was originally described in an
Experimental RFC in 1995 and is in wide use, but has not previously
been formally incorporated into SMTP. The 556 code was created for
RFC-nullMX. These codes are used to indicate that an Internet host
does not accept incoming mail at all (not just under particular
circumstances).
This is presented for publication as a Proposed Standard, as it adds codes
to RFC 5321, which is already standards track.
2. Review and Consensus
This document came out of discussions on both the apps discuss and ietf-smtp
mailing lists about (1) moving RFC 1846 to the standards track, and (2) the
nullMX idea. There was wide-spread agreement on both of those efforts,
including accepting nullMX as an APPS WG document.
The decision to create this document was mostly due to administrative ease so
that there was only one document updating RFC 5321 instead of two. The
nullMX document was then rewritten to point to this document. (The nullMX
document has been through 10 revisions since becoming an APPS WG document.)
There is widespread implementation of both of these return codes.
3. Intellectual Property
There is no IPR associated with this document, and the author confirms
compliance with BCPs 78 and 79.
4. Other Points
There are no downward references.
No errata exist against RFC 1846.
The IANA considerations section appears to be complete.