Unable to resolve mx record of 1 domain

I'll apologise for my naivety before I begin, dns aint my bag and I probably know far less than I should!

Having trouble sending e-mail to gtuk.com, did some basic fault finding and found that my dns server cannot resolve their mx record. As far as I'm aware, all inbound mail is ok.
I have 2 internal dns servers that forward to our ISP's dns on 195.224.255.70

My domain: johnrannoch.co.uk
internal dns: Win 2K3 AD Integrated
Using BIND?: don't know! sorry
external dns: 195.224.255.70 (cache2.dns.gxn.net)

If I run nslookup on an internal dns server, set type to mx and type in gtuk.com I receive a DNS request timed out message. If I set the server to 195.224.255.70, set type to mx and type in gtuk.com, everything resolves fine.

I've assumed that this indicates a fault with my internal dns but have checked, double checked and triple checked the settings to no avail. There's nothing in the event logs, I've cleared the cache, increased the timeout period, re-started the dns service but it still happens. I've even searched the registry for anything relating to gtuk but found nothing.

Please help, I'm a desperate man!

Try this, it'll probably fix your problem:

http://forums.devshed.com/showthread.php?t=124876

AlanGrah

That fixed it, thank you sooooooooooooo much