The service consist in..
it gives mail you for your dominion, yes, totally free, and occupies the space in the Windows live server,
the url is http://domains.live.com
Instruction in the portal page of domain.
is very easy.. only changing registries MX.
For example, in my web, i use this service of windows live (www.pirarpc.com) in a block in the left you can see...
screens:
you have a panel of your domains:

and, you can control your e-mails of your domain.

and, you can create a module for your web.

bye,
greetings:)
PD: Sorry for my very bad english, i speak only spanish LOL.