> you stop giving money to your mail host and get a different one.
I was entertaining the "host your own mail server" thought, I agree that if you don't host it yourself then you can change your provider if it fails you.
Much of the time, when it's for signup verification, especially for a free service, they just write "don't use @live.microsoft.com" underneath the email address box. The user wants to be signed up for the service more than the service provider wants a new user, at least by enough to use an alternate email address. Enough cases like this, and the user quits @live.microsoft.com.
Even if you host it yourself :-). The key is to own your domain.
This is when I decided to stop trying getting through with this and came back to paying a provider.