re :''In the trash there were now 13 new emails, all of them without a discription or contactinfo and all with the date 1-1-1970 at 14.00. '' Data had lost the real date. Thats usually a sign of a corrupted folder. If the date header disappears it defaults to listing the oldest possible date the computer could offer. re :''When I clicked on them, the screan was empty'' The headers in Index file could not connect to email to show content. re :''Yesterday I deleted a lot of old mails from the trash-box and this morning I clicked on okay when I was asked to compress the mailbox. '' Normally, I manually compact (not 'compress' that is totally different - no worries it was probably a translation issue) folders after deleting several emails and especially Inbox, Junk and Drafts as they get the most activity regardling deleting and moving emails. You describe something you would expect, the auto compact request was invoked after deleting a lot of emails. Compacting was the correct action. This creates a copy of the original file and scans the file for any emails that have not been 'marked as deleted', thus creating a copy containing only the good wanted emails. This is then stored as mbox file and the index updated. So all was ok at this point. You were using a reduced cleaned up file with emails from only recent weeks. re :''Today I was checking my email. Just when I read the last one, suddenly the screan changed and all the emails from my Inbox from the last two weeks were gone. '' I would be inclined to think this was the work of an Anti-Virus product that scanned the Inbox mbox file and others immediately as you finished reading emails. It may have been scanning an incoming email. The AV product did not like something and auto quarrantined the file. The trouble is AV products do not seem to understand that one mbox file can contain several emails, so end up trying to fix and corrupting mbox files or fix by deleting the entire mbox file. This means the index is left alone with headers that cannot show an email because it is either corrupt or deleted. re :''After the problemm occured I tried reparing the mailbox In, but nothing changed. '' Yes, you did the correct thing. The index may have been out of synch with the actual emails in mbox file. But, it was not, hence not a fix. Check the Anti-Virus product to see if it has quarrantined files that you might be able to recover. Advise: If you want the Anti-Virus product to scan Thunderbird files and folders and incoming emails, then make sure the AV is not auto fixing, it must ask what to do, so you can stop any auto fixing on any Thunderbird file or folder. Suggest you do this now. If you are talking about a POP mail account? Do you normally keep copies on the server ? Logon to the webmail account via a browser and see what is still on server. If you have emails seen in the webmail account Inbox, it is possible to get them downloaded again. * Access profile...in Thunderbird, 'Help' > 'Troubleshooting Information'. * Click on 'Open Folder' button A new window opens showing contents of profile name folder. * Exit Thunderbird now - this is important * Click on 'Mail' folder * click on 'pop mail account name' folder * Delete the 'popstate.dat' file - this keeps a record of everything that was downloaded. * Start Thunderbird. A new popstate.dat file will get created, but as it is new and empty, it will allow the download of everything that is currently in the Inbox on the server.