A. I would say all of it really. A better and more accurate process would be to create your labels, use Googles takeout service to get you mail labels in MBOX files. (that takes some days usually) They can later be imported to Thunderbird or any mail client that supports mbox imports.

Once you get your takeout, delete your labels and email on the google site, probably using a filter.

B. Work through the versions as offered. A lot of work has gone into leading folk through all the versions so all the relevant conversions occur to your data. Skipping can cause data isses, at this point mostly with address books and passwords. But just let it work it's way to current.

C. You might want to look at the labels that are converted to IMAP folders in the Gmail web interface.

D. What you appear to have is an IMAP account, which is syncronised to the Gmail server. Delete something on Gmail and it will be deleted on Thunderbird. See my comments on A. This is one reason I say it is best not done in Thunderbird directly.

Thank you for replying! I would like to make sure I am understanding you correctly:

I believe you are saying I should 1. Create the labels (that I want to sort through when I use TB) in gmail. 2. Then use Takeout to download my gmail labels into Mboxes 2a) Once I have the Mboxes I can import any of the Mbox folders at any time 3. While Takeout is creating the Mboxes, I should update TB to what it suggests - which for me is presently version 91 4. After importing the Mboxes, feel free to examine the emails and make decisions using Thunderbird ... but make the *actual* deletions and other changes within gmail rather than Thunderbird.

Would you please let me know if I understood correctly? Also, a Question: It sounds like my Thunderbird account will thereby be a mixture of old gmail structure and new Mbox imports if I update rather than start anew. It sounds like it will be messy and confusing ... is it not a better idea to start a fresh install, especially with the new wizard system?

Thank you again. I very much appreciate the time and help you've given.

UPDATE: Slight change of plans. I've just realized that there aren't many new senders since I was last active on my gmail, which meant I probably have every senders name I'll want to delete and unsubscribe from *already within my Thunderbird account.

So I've just learned how to stop Thunderbird from checking and downloading at startup, sorted my inbox by sender, and jiminy crickets!!!! I think my biggest problem is likely that there are some emailers who, once they got my email address, are BOMBARDING my inbox with outrageous amounts of emails.

Thus, I'm going to put off mboxing. I'm just going to update my existing Thunderbird to the recommended version, make lists of who I don't want to hear from anymore, and then go to my gmail and delete /unsubscribe from those.

This looks like it will make a huge and efficient difference and I can't sufficiently thank all of you who keep Thunderbird going. Without your dedication, I would not have a way to have searched by correspondent and see so quickly exactly who was gumming up my works. When it's clean enough to work with, Thunderbird will be, too :)

Time to make another donation to you guys. Thanks for everything.