re : Lost three months of emails in Trash folder....I really would like to have these emails back since they are all my back-ups

But they were in 'Trash' folder, so these emails were selected specifically as unwanted. Trash is like a temporary holding space, so if deleted in error you can easilly move it back to a suitable folder for storage. But ultimately, Trash means rubbish, for unwanted soon to be deleted emails.

I've never met anyone who puts all emails they want to keep, let alone as a backup, in the 'Trash' folder.

You can create new folders to organise and store emails for safe keeping. As this is an Imap mail account, you cannot consider any imap folder as suitable as a backup because they synchronise with server.

You could use 'Local Folders' mail account to keep copies of emails you need to keep, but backups are entirely different. That means keeping a copy of the profile or mbox files or even emails saved as .eml files in a different location eg: usb drive or external hard drive.

re: My other email accounts have emails in the trash folder dating back 10 years.

Strongly suggest you use suitable folders for emails you want to keep eg: ' Archives'.

re :IMAP settings and same missing emails on all devices Naturally, as this is what you would expect. Imap accounts see a virtual view of the folders located on the server. So all emails are stored on the server. When emails are deleted, they are deleted off server, so all imap accounts accessing the server would see the same.

If you recently used other devices to connect to server (I have looked on my other devices ( iphone, ipad, laptop ) ) and you deleted emails via those devices, then they would also be deleted off server, so when you started Thunderbird, it synchronised with server to show server contents. Hence deleted emails would be removed from the view as they do not exist.

Note: Many servers automatically empty the 'Trash' folder periodically eg: gmail. What server are you using ?

re : Also, I did see something that told me I have used 19% of my space used. That is refering to the percentage of used allocated server space.

Check some account settings which may be auto deleting emails.

• Right click on imap mail account name in Folder pane and select 'Settings'
• Select 'Server Settings'

Bottom right under 'Message Storage'

• uncheck 'Empty Deleted folder on Exit'

• Select 'Synchronisation & Storage'

Under 'Disc Space' section

• Select 'Don't delete any messages'

• Click on 'OK'

Suggest you also check out settings on all your other devices.

Normally, I'd ask if you have a backup of your 'profile name' folder which contains emails amongst other things such as address books, but as you said your backup was put all into the 'Trash' folder, can I assume you do not have any backup ?

Have you by any chance recently created a backup of 'profile name' folder ?