Emails may be being moved by a Message Filter. That filter could be in Thunderbird or on the webmail account. Because you use Imap, you need to make sure nothing is doing this on the server side (webmail) as well. In Thunderbird * 'Menu icon' > 'Activity Manager' '''Q: '''Does this give you any information on emails being moved to trash? '''Q: '''Do you have any 'Message Filters' working on that imap mail account where any filter mentions a move to trash? If yes, then recheck the conditions to make sure it is working as you require. Or disable them for now. * 'Menu icon' > 'Message filters' > 'Message Filters' Re: emails in Trash '''Q: '''Do you notice if they have been marked as 'Junk' ? There is a possibility that they are being perceived as junk and if your settings say move junk to trash then this could explain what is going on. * 'Menu icon' > 'Options' > 'Options' > 'Security' > 'Junk' tab * This is usually selected: 'when I mark messages as junk' * This is usually selected: 'Move them to the accounts 'Junk' folder' But do you have this selected ? 'Delete them' If yes, then select the 'Move them to the accounts 'Junk' folder' option. * select 'Enable adaptive junk filter logging' * click on OK '''Q: '''Have you set up the Thunderbird Junk Controls ? Check the imap mail account 'Junk Settings': * Right click on imap mail account in Folder Pane and select 'Settings' * Select 'Junk controls' * Select 'Enable adaptive junk mail controls for this account * Select any address book you want to use as a whitelist Destination & Retention * select 'Move new junk messages to' * Select 'Other' * Choose the imap 'Spam' folder on that account. * Suggest you 'uncheck' the 'Auto delete junk mail older than' option. * click on 'OK' Go to 'Trash' folder. See if marking as not junk will help to train the Junk filter and stop the auto moving. * Hightlight a bunch of good emails * Right click on highlighted emails > Mark > As Not Junk then * Right click on highlighted emails > Move to > Inbox of imap mail account.