Options on Deleting available for IMAP accounts. When you click on 'Delete' '''Move it into the Trash folder''' Then you can have a choice: * select to Empty trash when you exit Thunderbird * Manually right click on Trash folder and select to 'Empty Deleted' * Or wait until server auto empties Trash. This does vary and depends upon the server. '''Just mark it as deleted''' Email remains visible in same location, but now shows a line through to denote it has been marked as deleted but has not been put into Trash. When you compact the folder those emails should get deleted. In the same way all traces of 'hidden' marked as deleted emails get removed. This can be achieved in various ways: '''Manually:''' Right click on Folder and select 'Compact' '''Auto on Exit: ''''Account Settings' > 'Server Settings' - select checkbox 'Clean up (Expunge)on exit' '''Auto compact:''' when compacting will save eg: 30MB * Menu ≡ > Preferences > General * Scroll down to 'Network & Disk Space' section * Select checkbox 'compact all folders when it will save over 30MB' * option - select checkbox 'Ask evrey time before compacting' - this is handy as you would be better off knowing when it was about to occur, so you do not inadvertantly stop it or shut down etc. '''Remove it immediately.''' This may by pass the Trash folder and therefore could be a no-Undo action. Same as if using 'Shift+DEL' keys In an imap account like gmail which keeps all emails in 'All Mail' and uses 'labels' to offer a virtual structured view of emails, this may have the effect of deleting a label and not necessarilly deleting the email, so email may be archived in the 'All Mail' folder. It an have the unfortunate result of not reducing quota levels.