[RndTbl] email-receive blacklist?

Trevor Cordes trevor at tecnopolis.ca
Thu Apr 29 13:53:29 CDT 2021


On 2021-04-29 Colin Stanners wrote:
> I'm afraid that if I understand the situation correctly, the MXVerify
> result is not an non-error, it is a real problem, and the likely
> cause of your issue.

See the Gilbert reply.  This doesn't jive with the understanding of
these 2 old hands.

> That serverfault link is unrelated, you are not sending emails only,
> this discussion is about your domain receiving email.

Ya, but its answer re: RFC5321 is correct:

2.3.5.  Domain Names
   Only resolvable, fully-qualified domain names (FQDNs) are permitted
   when domain names are used in SMTP.  In other words, names that can
   be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed
   in Section 5) are permitted, as are CNAME RRs whose targets can be
   resolved, in turn, to MX or address RRs.
===

So per RFC is the receiving domain can either resolve to MX, *or*
direct A RR (as my domain did).

Further:

5.1. Locating the Target Host
   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.
===

As far as I can tell, 5321 is still in force and not superseded.

I had a valid, empty (non-existent) MX record set.  That should be
valid.

If you have a different understanding, feel free to RFC-enlighten us!


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