[exim] mail server rejecting all mail

I'm setting up exim on another system. I find that mutt can receive
mail, but not send it.

The new system is sidux on a Thinkpad X61s. I need to describe the
physical setup in case that may be the problem. The Thinkpad is
connected to a modem router that is used by my desktop machine for
Internet access. I rely on DHCP, and the resolv.conf file on the
working desktop picks up just the address of this router
(192.168.1.1). On both the desktop machine and the laptop connected to
its modem router have this address in their resolv.conf file.

The error message back from the server when I use the laptop to send a
message to addresses I know are quite valid:

SMTP error from remote mail server after RCPT TO:<the address>
host mymail.myregisteredsite.com [209.237.134.152]:
553 sorry, that domain isn't in my list of allowed rcpt hosts
(#5.7.1)

I can ping both mymail.myregisteredsite.com and 209.237.134.152 from
the laptop.

I'm mystified by the error message, for obviously the DNS knows of the
recipient domains, and I can only infer it has a lookup problem
because it doesn't know who I am. Can anyone straighten me out on
this?

So the problem must be exim setup, but the setup is the same on the two
machines with one exception. That is, on my desktop I now see that I gave
my system mailname as "teufel.hartford-hwp.com", and should have
provided just the domain, "hartford-hwp.com. This error proves to be a
nuisance for some newsgroup headers. On my laptop exim configuration I
corrected this and just have "hartford-hwp.com".

Initially for the laptop, in reply to the configuration question
whether to Hide local mail name in outgoing mail? I had said NO. But
because of the problem gettng mail out, I changed it to YES, which is
what I have on my desktop. Now for both machines, the local mail name
is set to be "hartford-hwp.com".

Otherwise, exim on the two systems is configured the same.

Haines Brown