ISPs often levy charges if you move away from them and want to keep using the email address you had with them.
An excellent ArsTechnica overview (and tutorial) of Helm Personal Email Server, which provides the hardware and services you need to easily host your own email.
A comparison between phone and email as communications protocols and some very personal conclusions about which I think is the better.
The big tech companies rarely have genuine email support, which I think discriminates against the hard of hearing. Not only that, email is the most efficient way to provide support in most cases.
There's no easy way to add Microsoft Exchange aliases on iOS like there is on MacOS. In this article I present an ugly but effective workaround.