I'm assuming you are usig imap account, because they only show what is on the server. When Thunderbird was pointed to use a new empty server, it deleted everything in the account, so it would now only show what was on the new server. So only new emails received to that server.

You cannot just copy all the files from a 'profile name' folder as it would start overwriting account information etc which you do not want. All imap account emails that was copied back would be immediately removed when you restarted Thunderbird because the imap account would first synchronise with server to show what was on server and delete all the actions you had just attempted.

So this means you need to locate the backed up files that contain the emails and this time copy paste them into the 'Local Folders' mail account. The 'Local Folders' mail account is independent and does not synchronise with any imap account.

• Exit Thunderbird.
• Access the backup 'profile name' folder.
• click on 'ImapMail' folder
• click on the imap mail account name folder to see contents.

You should see mbox files. They are files with same name as the folders you see on the server. They do not have any extension and they contain emails. OR they may be empty but required because they contain sub folders. Files with .msf extension are just index files used by Thunderbird, they do not contain emails. If you have subfolders you will see folders with a .sbd extension.

• You need to copy all the mbox files and folders with .sbd extension.

Whilst drag and drop is great for moving folders, I would advise you use the 'Copy' option as it is always repeatable if required.

• Access the location where your current Thunderbird 'profile name' folder is located.
• This time click on 'Mail' folder
• click on 'Local Folders' folder to see contents.
• Paste all those mbox files and .sbd folders into the 'Local Folders' mail account.

I've posted an image below which shows a typical view of files and folders in an imap account on the left and on the right a typical view of 'Mail'/'Local Folders'.

When you have copies of all the mbox files and all the folders with .sbd extension copied into 'Local Folders' folder.....Start Thunderbird

When you start Thunderbird all your emails should appear in the 'Local Folders' mail account. The imap account will also do the first synchronisation with server to show what is on server. Now, you have a choice. EITHER choose to leave all the old emails in 'Local Folders' where you will have access to them and only keep new emails on server ; also the old emails will not use up your server quota OR you can now highlight batches of emails in the 'Local Folders' mail account, right click on highlighted emails and choose 'COPY to' and select the relevant imap folder. This action will then upload those emails to the server. Please note: only use 'Copy to' as this will preserve the original if something goes wrong. Only upload in batches as there is a lot of jibber jabber going on between each individual email and the server. Be patient as some server do have limits on the amount or size that can uploaded within a given period.

The video is generally ok if you still have the same settings and for some reason need to replace a new profile data with old profile data. eg: Moving to another computer or Old profile corrupted, so need to completely remove it and use the backup to recover files. But the accounts and the server settings were not being altered to point to new empty servers. So the new server settings would be in the current 'profile name ' folder 'prefs.js' files etc, but they are not in the backup copy, so you do not want to overwrite certain information. Or even if same server settings, the servers folders which the imap account accesses were not empty.

If server is empty due to loss of emails or empty because eg: new webhost, then you need to only copy and paste the actual backed up files containing the emails into the 'Local Folders' mail account first and then follow the copy to procedure to upload back onto the server.