I see your problem
To Unpark (Activate) Your Domain Name
1. Log in to your Account Manager.
2. Under the Domain Names section, select Manage Domains.
3. Click on the domain you want to unpark.
4. In the Domain Details section on the right, click the plus sign next to Namservers Summary to expand it.
5. Select Click here to see details or to modify.
6. If you are hosting with us, select Default Hosting Name Servers. If you want to use other name servers, select Custom Name Servers and enter the name servers that you would like your domain name to point to.
7. Click Save Changes.
If they are not hosting you, give them the nameservers that you will add. Primary and a failover I suspect. Looks like you will be managing your own domain. Now if you do that look into milter and get aboard the DKIM train :-)
thanx,
bill
