[Windflier]

I love Thunderbird, but if you ever change your ISP, forget it. There goes your address.

It’s why I finally gave up and started using a Yahoo mail account. My address follows me wherever I move, no matter what ISP I have.

[oh8eleven]

I love Thunderbird, but if you ever change your ISP, forget it. There goes your address.
Not sure what you mean. You can change your email host from Gmail, Hotmail, Yahoo, etc., in TB as often as you want.
And even if you have more than one email account on different servers, you can add them all to Thunderbird.
All you have to do is create a new account for each one within Thunderbird that points to the new server(s).
Google "how to set up thunderbird for XXXXX" where XXXX is your email provider, and you'll find detailed set up instructions.
Setup a new TB account for each email address.