You can have multiple accounts within Thunderbird. Two versions of Thunderbird are not supported, but you can achieve your objective with just one version.

Thanks for the quick reply David!

After reading your reply I went out to Account Settings and found where I can add a new account to my Thunderbird program. When adding a new account will that give me two separate T-Bird screens, or will email for both accounts come into my current screen that shows my existing folders? Also, I'm assuming that my current ISP (Comcast) will forward my incoming and outgoing mail for each separate account. Do you know if ISPs will do this?

Currently Comcast is handling my incoming and outgoing mail fine, but my strange situation is that I'm still connected to Surewest (now CCI), as it shows in my email address, which is who I formerly had as my ISP, but no longer do. For some reason, they allowed me to keep using their email system for many years after I was no longer one of their customers. But now they no longer allow me to sent, or reply to mail through Thunderbird, although I can still do this on their webmail service.

My goal is to separate from Surewest (CCI) completely, create a new Comcast email account and address, but want to do this in a way that I don't lose my saved messages in my current T-Bird/Surewest folders.

I hope I'm making sense here, and thanks in advance for any further information ~ Bill

First, Thunderbird treats all accounts independently. That is, it's as though two copies of Thunderbird are running. Each account will have its own inbox, sent folder, trash folder, etc. If you're going to lose the surewest account soon, I encourage creating local folders and copying the messages there to ensure they don't get lost. Once you have captured everything you want, you can then delete the surewest account.

Thanks again David!

Good clear explanation of what I'm trying to accomplish, and I believe I can proceed from here. I didn't realize that the Local Folders could actually save our mail and will copy my existing messages to them first. I think that being brought up on typical webmail prevents some of us from realizing all of the capabilities built into Thunderbird, which outshines all of the others I've ever used.

I appreciate your help!

~ Bill

You're very welcome. :)