If the Trash was emptied, then this could have occurred in two ways. You may have a setting to 'Empty Deleted' folder when you exit Thunderbird. OR the server has an auto empty the Trash every x days. As you have an IMAP account, if server emptied Trash, then the results of this would be shown in the Imap account Trash folder when they synchronised. Most emails that are put into Trash were originally in the 'Inbox', so it is worth checking both locations. To see if there is anything in the imap 'Inbox' and 'Trash' folder: Help > Troubleshooting Information Under 'Application Basics' section Profiles: click on 'Open Folder' A new window opens showing the contents of your profile name folder. Exit Thunderbird now. You will see a 'Mail' folder - note this - it contains 'Local Folders' folder. Click on 'ImapMail' folder click on the name of imap account folder If you download full copies then you should see an 'Inbox' mbox file. It has no extension and it contains emails. You will also see an 'Inbox.msf' file. This is an index file used by Thunderbird and it does not contain emails. You will also see the same for the 'Trash' folder. You can open an mbox (no extension) file using 'Notepad' or other text editor program. Oldest emails are at the top. If you see emails try this: Close the file. Create a copy of the file. Rename the copy eg: OldInbox or OldTrash Then move the copied/renamed file into the 'Local Folders' folder located in the 'Mail' folder. Open the 'OldInbox' or 'OldTrash' using Notepad. Each email may start with : example * From - Sat Feb 1 18:49:55 2020 * '''X-Mozilla-Status: 0001''' You need to make sure the 'X-Mozilla-Status:' has the number '''0001''' Edit as required working down through document. Then save file. Start Thunderbird.