OT: CommuniGate Pro rejects email using bogus rules?

I am running into a problem with an email server telling me that it
has a DNS server failure. From what I've been able to see by
telneting to port 25 of the server it's using "CommuniGate Pro".

Deferred: 472 userid@somedomain.org DNS server failure

The error is shown above with the name changed to protect the
innocent.

Now what gets me about that is I indeed do not have an IP address
assigned to "somedomain.org" though I do have one assigned to
"www.somedomain.org"

The point is that I have an MX record that sends email to a relay
server with a completely different domain name.

While I've got a call into their IT, I'm expecting an answer that
there is nothing they can do. I'll probably add the IP for the domain
name because my client has a lot of traffic with that domain.

That being said, the email server in question should be looking at the
validity of the MX record, not the validity of a web server that
doesn't receive email.

Maybe someone familiar out there with that email server software knows
of a setting or configuration that would make the email server do the
right thing, but I'm not holding my breath.
Mostly this is just a rant.
=== Al