The archive folders reside in your Tbird profile folder just like the other folders, unless you change their locations/paths. Archiving is not intented to keep the size of your Tbird profile folder small or to free up disk space. Archiving is merely a way for you to stow away (old) emails that are not currently needed, but could be needed for reference much later. They are moved out of your inbox to keep your inbox neat and focused on current cases/matters, but remain easily retrievable when required. Your method achieves the same, the main difference being your method involves manually creating the archive folders/subfolders according to how you wish to organize the messages you wish to stow away in them and manually moving the messages to their respective archive folders. Tbird's archiving options are a convenience for those that find them useful. For example, if you're manually creating archive subfolders for each month or year, then you're manually doing the exact thing that Thunderbird is able to do for you on the fly. All you'd have to do is configure the archiving options once and Thunderbird would take care of the folder creations and moving of messages automatically when you click the Archive menu option or toolbar button. You would want to use Tbird's archiving options to save you the trouble of manually having to do the same thing.

Thank you so much for the clear reply. Archiving has been confusing me for some time. Perhaps some of that background you provided would be helpful in the TBird manual. One more question please. On IMAP (in the cloud) I have set up some folders for temporary use, but they do not match the dozens of folders that I have on my local drive. If I wanted to use the archiving feature with archives by year, it sounds like I would have to establish the same folders in the cloud as I have on my local drive and then select "Yearly archived folders" and "Keep existing folder structure of archived messages." Is that correct? If so, for my way of working, where I prefer removing most messages from the cloud as quickly as possible (to keep them away from prying eyes) archiving seems like it offers me nothing.

You can find a lot more and perhaps better explained information on the same via Google. Get started here https://www.google.com/search?q=archiving+emails

No, you wouldn't have to create the same local folders in the cloud for archiving. In Tbird's Account Settings, you are able to choose where archived messages are stored. The Archive Options button is inactive (greyed out) if the selected folder is an IMAP folder. The button becomes active if the selected folder is a local folder, which you've already created. All you need to do is configure Tbird to use a local folder for storing archived messages, then configure the archiving options as you desire. When you archive messages, they'll get moved from the cloud to your local folder.

If I understand this correctly, my local Archive is always dublicated in the "imap sky" so that if my PC breaks down, the Archive can be restored from imap when my PC is fixed??? I have previously had this problem, and a whole chunk of emails were lost forever. EHH

If I understand this correctly, my local Archive is always dublicated in the "imap sky" so that if my PC breaks down, the Archive can be restored from imap when my PC is fixed??? I have previously had this problem, and a whole chunk of emails were lost forever. EHH

No, it's NOT. A local archive solely resides on your computer's storage. That's what "local" is all about vs "remote" or "sky" as you put it. If measures are not put in place to mitigate data loss, then you will lose your emails permanently when the storage hardware fails, so when you opt for an offline/local archive, you take the responsibility of safeguarding against loss. Not even Mozilla is liable for your data when using Thunderbird.