[fwd] Re: [vox] Re: Earthlink "test" messages to 'postmaster'

[Micah J. Cowan]

On Tue, Jun 28, 2005 at 10:34:38PM -0700, Bill Kendrick wrote:
> 
> ----- Forwarded message from "Karsten M. Self" <kmself at ix.netcom.com> -----
> 
> On or about the 19th, Earthlink modified its outbound email server in a
> way that makes it impossible to send to a host that doesn't have an MX.
> Instead I get a bounce message from ELNK's smarthost of the form:
> 
>     This message was created automatically by mail delivery software.
> 
>     A message that you sent could not be delivered to one or more of its
>     recipients. This is a permanent error. The following address(es) failed:
> 
>       vox-tech at lists.lugod.org
>         host lookup did not complete: retry timeout exceeded
> 
> 
> This is in violation of recommendations and standard practices, if not
> RFCs.  SOP is to fall back to 'A' records where an MX doesn't exist.

It is in violation of RFCs as well. RFC 2821, section 5 makes it clear.
When RFC 821 came out, DNS didn't actually exist yet, and existing
host-name resolution provisions didn't have a MX-like facility, FWICT.
But soon after DNS was invented, RFC 974 made it clear that fallback
to the actual host was required in the absence of MX records.

I've always thought of the "host" portion of email addresses as referring
to an actual host (with corresponding A record, or at least CNAME), and
of MX records as a sort of aliasing mechanism. I'm surprised (but not
very) that Earthlink would do something so broken.

Congratulations on rejoining the land of the communicative! ;-)