Intermittent Sender Domain Must Exist errors from remote SMTP hosts

[Kevin Darcy]

What are you giving as your MAIL FROM in these SMTP conversations? The
zone "example.com" may be perfect, but if your MAIL FROM is giving
"user at internal.example.com", where "internal.example.com" has no
retrievable data on the Internet, then SPAM-paranoid mailers will
probably reject it. It's become a necessity these days to rewrite sender
envelope addresses, for just this reason. If you're balancing your load
amongst multiple outbound gateways and only 1 of them is misconfigured,
this might explain the intermittentness of the problem.

Of course, I'm only speculating. Maybe you really do have a
_bona_fide_ DNS problem. But since your zone has already passed
DNS Expert, I think it's worth investigating the other possibility...


- Kevin

robertd040 at aol.com wrote:

> Hi everyone,
>
> I'm having an intermittent problem with outbound email.  I will
> intermittently get an error from a remote smtp host that indicates
> that the reason for the rejection is "Sender Domain Must Exist", I've
> also seen "DNS: FAILURE" or "Sender Domain must Resolve".  I've
> checked and re-checked my zones, I've verified that my MX records are
> correct (even though I don't see this as a problem because the MX
> record is for OTHER people to find MY mail server with), I've
> confirmed that my servers are delegated our reverse zone,
> (in-addr.arpa) with our ISP, (Cable and Wireless)  , and from the
> Internet all forward resolution works perfectly.
>
> I've been hearing a lot about anti-spam filters that SMTP hosts employ
> to verify the validity of a SMTP message but I'm not sure this can be
> ALL the problem.
>
> I've got 6 zones that I'm currently "hosting" with two name servers.
> All the zones are registered with Network Solutions and all the zones
> have the same two DNS servers.
>
> ex. (truncated whois output)
>
> XXXX.org
>
> ns1.XXXX.org    123.123.123.123
> ns2.XXXX.org    123.123.123.123
>
> and
>
> XXXY.org
>
> ns1.XXXX.org    123.123.123.123
> ns2.XXXX.org    123.123.123.123
>
> etc..etc..etc..
>
> I could include a huge amount of detail regarding my zones but it's
> pretty basic and I've run tools like DNS Expert (miceandmen.com)
> against the zones and they come up clean.
>
> My two real questions are;
>
> 1).  Have I done a bad thing by "hosting" several different domains
> with the same two name servers. (I don't think so)
>
> 2). What are these remote smtp hosts doing so strange that they won't
> correctly resolve who's authoritative for my zones? and why is it
> intermittent. (usually I can re-send and the mail will go through).
>
> Thanks for anyones help.
>
> Robert