Compacting folders deletes any messages marked for deletion. It does not zip them up for future access.

Here is the documentation for compacting folders.

http://kb.mozillazine.org/Thunderbird_:_Tips_:_Compacting_Folders

I am baffled- so when Thunderbird asks me if I wish to "compact folders" it actually means it is deleting all of my mail? My account settings are set to save all mail in 'all mail'. (not delete after 60 days, etc)

But all the mail I need for documentation, which I access every year, is gone completely. It seems Thunderbird has not archived anything and I have been screwed up completely.

Where in the world did you read Deleting All My Mail? I have reread my answer several times and cannot seem to find that in there.

When you mark a message for deletion it does just that. It marks it for deletion and hides the message. It is not truly deleted until you compact. My point is that unless you deleted your important mail they should still be there somewhere. Your question was about compacting and thinking it put your messages in a nice little box for safe keeping and now you want to open it. I have to agree that Thunderbird did a horrible job of naming this process because most are like you and do not understand what it actually does. I included the link to the explanation of what compacting means in the Thunderbird world. Your messages may still be available to your but finding them has nothing to do with compacting.

Thunderbird does not archive anything unless you use that process by selecting the message and pressing a. You have the option to setup where you want that archive to go and what folders to make.

The All Mail folder is a goofy gmail arrangement. If you have problems with that then you need to address that with Google. If you go into your gmail account on the gmail site do you see the messages you are hunting in the All Mail folder there?

Yes, sorry- and thanks for your help! Compacting would only delete those messages marked for deletion. But I periodically receive a question box from Thunderbird asking if I would like to compact folders and once or twice I clicked "oK" I fear now that it was asking if I would like to delete everything, not just the deleted folder. I should start a new topic asking why on earth Thunderbird disappeared all my mail.

Maybe you could read the compacting documentation that I provided. This will answer your question. It is not asking if you want to delete all your messages. Only to permanently remove the ones marked for deletion.

Did you go to gmail and look in the All Mail folder for your messages if that is where you have it set to store them?

Then it is not the compact function. Alas, the mail is not in Gmail either. Oh well! Thanks for your help!