In an IMAP maila ccount you can choose what to do when you delete a message. Right click on imap mail account name folder and select 'Settings' Account Settings opens in a new tab Select 'Server Settings' You have three options: When I delete a message: * 'Move it to this folder' and choose the imap trash folder on the account. This moves email from whatever folder it was in and puts it into the imap Trash folder.' * 'Just mark it as deleted' this leaves the email in same location, but puts a 'strikethough' line through the email in Message List' * 'Remove it immediately' removes email from folder. You also have the option of choosing eg: Move to this folder - trash on imap account But on occasions you may want to delete and by pass the TRash folder : Use 'Shift' + 'Del' keys on keyboard. Please remember - compacting will remove all traces of emails that are hidden and marked as deleted. You need to do this on a regular basis to maintain a healthy Thunderbird.