sorry 'bout confusion. Let me clarify:
I have a DH account. I also have a domain which is registered with Network Solutions (let me call it ns.com). I would like to point ns.com's MX records to DH's mail server, effectively using DH as ns.com's email service provider.
Since DH is not ns.com's registrar, I assume it wouldn't know what to do with messages addressed to email@example.com once they arrive at DH's mail server.
To enable that message routing, I think I need some way of telling DH that I want these messages.
I have not seen a tool that allows to do that, except that I migth be able to add domain "ns.com" through DH's control panel even though this domain's DNS records are kept elsewhere.
Is this how it is done?
I have the feeling I make this more complicated than it is, but want to prevent screw-ups in the process. Your advise is very much appreciated.