On my local area network :
(The IPs configs uses the same submask, DNS, etc...)
eMail Verifier gives good results under Mac OS X.4.7,
and, for the same e-mail list,
MX Result <
[email protected]> -> [[Bad e-mail] No MX found for [MACHIN.FR]] under XP...
(Nslookup command gives me good answers...