use the import export tools add-on to import your old mail from the backup to local folders.

Slowly add them back to the IMAP account (less than 500 at time) and allow the updates to sync back to the server.

See https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/

The tool said it couldn't copy all the remote emails to the local folder. I didn't change any options, only did export keeping folder structure.

I am wondering why when i connect to the internet with my old profile, it goes back to where it is on the server. Would i be able to upload old messages slowly?

I forgot to say it was IMAP so i can't export nor copy the server side of my folders to the local folder when I'm not connected to the internet. Copying works on the folder structure of one of my folders but not the emails (actually it does copy 1 or 2 emails) I thought to copy all my emails (from my backup profile) offline to the local folder and then copy them back to the server folder online. I don't use "offline" option of Thunderbird. I just unplug my computer.

Thank you

I am wondering why when i connect to the internet with my old profile, it goes back to where it is on the server.

This is how IMAP works.

I forgot to say it was IMAP so i can't export nor copy the server side of my folders to the local folder when I'm not connected to the internet.

You do need a local offline copy in order to be able to do that. In Thunderbird it's called 'Synchronization'. https://support.mozilla.org/kb/imap-synchronization

I thought to copy all my emails (from my backup profile) offline to the local folder and then copy them back to the server folder online.

That's exactly the way it works. But then you do need the offline copy of your messages from the backed up profile.

What many people don't seem to understand: using an IMAP server doesn't make a backup obsolete.

Well i have a backup! I see all the emails offline but can't copy them. I have the body of the emails not just the header.

Do you mean i need to use the "offline" option from Thunderbird to copy the emails to local? I thought i needed to do that while online ?

Not sure how to go forward.

I could copy one folder (and its structure and emails) to the local folder offline. I do have 2 more and nothing happens when i try to copy a second.

I have the body of the emails not just the header.

Good.

Do you mean i need to use the "offline" option from Thunderbird to copy the emails to local?

No, you don't have to be in offline mode for this.

I thought i needed to do that while online ?

You don't have to be online either, as you're only accessing local stuff, and not any servers requiring network access.

I do have 2 more and nothing happens when i try to copy a second.

What exactly are you doing when you copy (using ImportExport Tools, Windows Explorer, command line)? Please be more specific. Presumably your mail files are large, so disabling anti-virus on-demand scanner for this may help.

Ok I think i go a bit too fast with my replies. Thunderbird was still copying the first folder when i tried to copy the second. Now i have all my folders in Local folder using ALT drag to copy (I had to copy the emails from sent box manually into a folder i created as it wouldn't copy like the others) Now I want to merge the emails from Local folder to the IMAP folder and thus upload them to the server. Matt in a previous post said to copy them back slowly. I have Loads of subfolders within 3 folders so if there is a more direct solution, I would of course prefer!.

Thunderbird was still copying the first folder when i tried to copy the second.

I'm not sure what that means, as you were supposed to copy files outside of Thunderbird. But as long as all messages are in Local Folders now you should be good to go.

Matt in a previous post said to copy them back slowly.

Email servers are not designed for mass transactions, e.g. Google is throttling mass up- and downloads. Therefore, take your time.

Only copy messages, not entire folders with subfolders.

Copy messages in batches, not all at once if the folder is large.

Verify the result. I.e. before copying the next batch, check all messages made it to the server from the previous batch.

Use Copy, not Move. If something goes wrong, you still have the local copy, which you can delete after a successful transaction.

Select the messages for a batch - right-click a selected message - Copy To - chose destination account/folder. Don't use drag n drop.

It seems i need to do it manually. I thought so. Thank you for detailed walk through. thanks a million for helping.

One last thing. Once the messages have been copied back to the server, also keep an eye on the status of your offline copies for the IMAP account. That may take a little time too, but make sure it's there at some point.

In other words, what you upload to the server, will also need to be downloaded as IMAP offline copy, so you can create local backups.

I copy the entire profile. How does that differ from local backup?

Also i use AutoArchive Reloaded to archive emails older than 500 days to free space on the server. I am not that keen on it as it creates new folder structure for each year. Perhaps offline backup would have been better but then no free space created on the server. In that case I am wondering how reorganise (copy the archive back to normal local folder) without having to do all manually. I have hundreds folders. Any idea?

I copy the entire profile. How does that differ from local backup?

It doesn't. Copying the profile is what I mean.

Perhaps offline backup would have been better but then no free space created on the server.

I don't think I understand what you mean. In any case, if you run out of space on the server you'll need to move messages off of the server to your 'Local Folders' account. That you can then backup locally.

I am not that keen on it as it creates new folder structure for each year.

That method works for me using the Thunderbird built-in Archive feature.

I have hundreds folders. Any idea?

I use as few folders as possible.

When your problem has been fixed can you mark the thread as 'Solved' please? Thank you.

I thought i wrote something more but can't see it in this thread. I couldn't see any "Solved" button. Did you chose it? Thank you