Neither, it’s standalone and expensive. :) Though I think you can get it as part of a 365 subscription.
It’s really for buiness use, connecting to exchange server and what have you. Overkill for home use.
Aww bummer, maybe I’d be better off with postbox?
Postbox has a 30 day trial and 60 day money back guarantee. They last had a spring sale with 20% off that ended May 7. Sometimes there are deals if you follow their Twitter.