dates back to April 201. I would expect that 19 years is sufficient
time
for the news to have reached Redmond, WA.
I think thats actually 1819 years so most definitely long enough to get
the memo…
I stopped believing long ago that Microsoft adhered to any standard in
earnest. To me, they always seemed to be more about
implanting new standards that the world would then follow…
On 17 Sep 2020, at 18:11, Viktor Dukhovni wrote:
On Sep 17, 2020, at 9:30 PM, @lbutlr <krem...@kreme.com> wrote:
This may have changed, but I doubt it. If you do not have MX records
there are definitely mail servers out there that will not send mail
to you. Exchange for one at least used to refuse to deliver mail
without
an MX record. I don't know if this is still the case as I am
thankfully
at least 5 years from having to deal with anyone on Exchange server.
RFC 5321 was published 2008:
https://tools.ietf.org/html/rfc5321#section-5.1
The lookup first attempts to locate an MX record associated with
the
name. If a CNAME record is found, the resulting name is processed
as
if it were the initial name. If a non-existent domain error is
returned, this situation MUST be reported as an error. If a
temporary error is returned, the message MUST be queued and retried
later (see Section 4.5.4.1). If an empty list of MXs is returned,
the address is treated as if it was associated with an implicit MX
RR, with a preference of 0, pointing to that host. If MX records
are
present, but none of them are usable, or the implicit MX is
unusable,
this situation MUST be reported as an error.
But even prior to that:
https://tools.ietf.org/html/rfc2821#section-5
Once an SMTP client lexically identifies a domain to which mail
will
be delivered for processing (as described in sections 3.6 and 3.7),
a
DNS lookup MUST be performed to resolve the domain name [22]. The
names are expected to be fully-qualified domain names (FQDNs):
mechanisms for inferring FQDNs from partial names or local aliases
are outside of this specification and, due to a history of
problems,
are generally discouraged. The lookup first attempts to locate an
MX
record associated with the name. If a CNAME record is found
instead,
the resulting name is processed as if it were the initial name. If
no MX records are found, but an A RR is found, the A RR is treated
as
if it was associated with an implicit MX RR, with a preference of
0,
pointing to that host. If one or more MX RRs are found for a given
name, SMTP systems MUST NOT utilize any A RRs associated with that
name unless they are located using the MX RRs; the "implicit MX"
rule
above applies only if there are no MX records present. If MX
records
are present, but none of them are usable, this situation MUST be
reported as an error.
dates back to April 201. I would expect that 19 years is sufficient
time
for the news to have reached Redmond, WA.
--
Viktor.
