Since you didn’t get a reply... T-bird is a local desktop client. You can configure it to go fetch emails from existing email accounts or you can make custom accounts using T-bird’s affiliated email services.
https://support.mozilla.org/en-US/kb/new-email-address
Thank you. I’ll check in to it.
When we moved last year and had to change our email address, it was a real bugger notifying everyone. And we forgot a few. Didn’t want to go through that again.