Thank you Keith. It is clear now.
Regards,
Geethapriya
On Thu, 2019-09-05 at 00:15 -0400, Keith Moore wrote:
On 9/4/19 10:35 PM, Geethapriya Liyanage wrote:
The RFC3463 defines new mail system status codes. However, the
excising mail servers are still using old status codes. Is there a
work happening to change the current mail systems status codes
according to this RFC.
As you have observed, there are two kinds of mail codes. SMTP
"reply
codes" are 3 digits long: 2xx is normal, 4xx is temporary failure,
5xx
is permanent failure, and so on. Those reply codes have been with
us
since at least RFC 821 and have not changed (except that a few new
codes
have been added). Those codes affect the SMTP state machine - they
tell a client, for instance, whether it can continue the SMTP dialog
or
whether it should abandon attempts to send the message.
The RFC3463 "enhanced status codes" (note the subtly different name)
are
intended to provide more detail for delivery and non-delivery
reports
(also known as "message disposition notifications" or MDNs), and to
be
language-independent. There's never been an intention to change
the
SMTP reply codes, because this would break existing SMTP clients.
But
there is an SMTP extension called ENHANCEDSTATUSCODES that allows an
SMTP server to return an enhanced status code to a client, for use in
an
MDN.
When designing the MDN format we realized that the 3-digit SMTP
reply
code scheme didn't allow for enough different codes to reflect the
different reasons for message delivery failure, so we needed a new
scheme.
Sorry the similarity between the names is a bit confusing. In
hindsight we probably could have made that a bit clearer.
Keith
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