This is great question my first question to you is do you plan on being with that internet provider for many years or do you plan on moving. when you get your internet disconnected usually 30 – 90 days after that they terminate your email account granted you may get phone support with that email service as well.
I would suggest checking out the login page alot providers use squirrel mail or roundcube which I’d tell you just stick with gmail, hotmail. yahoo, aol. those are the most easy ones to to get working with most of all your devices. sometimes your internet provider may not have the host name even on there website. I know a attmail looks cool but it could be just pain in the end.
Gmail – Support site
Yahoo – doesn’t seem to have email support page.
Hotmail – Support site
At the end of the day you should just use gmail its easy and just simple.