[EXIM] Wildcard MX record causing problems

I've come across a problem whilst configuring Exim to work with my dial-up
Demon Internet account (under Linux). I'd like to verify the sender's
domain but this is proving rather difficult because of what seems to be a
wildcard MX record for demon.co.uk. If Exim tries to perform an MX lookup
for (e.g.) 1234.com the resolver tacks on .demon.co.uk and the lookup
succeeds. Exim also re-writes the reply path with this "new" domain name.

I guess I could stop the resolver doing this with something like "search ."
in resolv.conf, but is there an Exim configuration option that might help me?

Thanks in advance,

Mike
-- 
Mike Zanker                | Email: A.M.Zanker@???
Network Services Group     | Tel  : +44 1908 652726
The Open University        | Fax  : +44 1908 652193
Milton Keynes, UK          | PGP public key available

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