Some ISP's (actually use to be most but that is changing) don't allow you access to the e-mail and the rest unless you connect through them. I use AT&T as my backup ISP, and they were that way for a very long time, but now they do allow outside access. Before that, unless you dialed into an AT&T port or cabled modemed in through them, you didn't get anything from them.

Check with your ISP to see if they allow it. If they do (again most do now) they will probably have a page telling you what you have to do, for example you may have to sign in through them, check a box saying allow access, and then you are fine.