I am moving my domain -- let's call it mydomain.com -- from hosting provider A to hosting provider B. Along the way, I am also moving my e-mail address -- let's call it me@mydomain.com -- from host A to host B. I know how to make a backup copy of the e-mail account at host A, how to give it to host B, and how to get host B to restore the backup on their server. I have done this, successfully. I know how to copy the e-mails on host A to a local Thunderbird folder, how to select the new messages (post-backup), and how to copy them to host B. I'm about to change my domain registration to point to host B. Eventually, all e-mails sent to me@mydomain.com will be delivered to my e-mail account on host B. However, while this change propagates through the Internet, some e-mails will continue to be delivered to host A. Is there any way that I can follow both accounts -- the one on host A, and the one on host B -- on Thunderbird, at the same time? The accounts use the same address of course -- me@mydomain.com. Inside the guts of the accounts, they use different ISP addresses -- for example, server123.hostA.com and server890.hostB.com. However during my efforts to create two e-mail accounts on Thunderbird, with two different ISP addresses, Thunderbird has repeatedly seemed to be bewildered by the simple fact that the accounts on the two different servers have the same "address," namely, "me@mydomain.com." Is this a terminal condition? Or is there a way that I can help Thunderbird through its confusion?