$500.00 US last I checked...
Need to get NTList if you want to do lists...
Need to get NTDomain if you want to do multiple virtual (as opposed to
aliased) domains...
I believe they both cap out at $500 US a peice for unlimited as
well...
More info at http://www.ntmail.co.uk/ or http://www.net-shopper.uk.co/
regards
Sam