It would be nice to add a "Empty Deleted Items Folder" like MS Outlook has.
Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.
This was an option in the drop down when you right clicked on the Deleted folder in previous versions of TB but seems to have been removed in the latest release. It was also on the Junk and Spam folders drop downs.
However, I've just noticed that it usually appears the first time you invoke the drop down on all 3 folders (although on the Spam folder's drop down it's called " Empty Junk") but subsequently doesn't always show, so this isn't a reinstatement request, it's a bug report!
Excellent idea! Another would be to auto-empty deleted items box on exiting from T'bird.
This is the option in my copy of Thunderbird in the account settings > server settings.
This is the same option that as far as I recall has been there for more than a decade.
I have an empty trash option on my right click menu for trash and spam/junk. They do however only appear if the icon on the folder is the spam/Junk and Trash/deleted. Sometime IMAP server fail to correctly identify those folders and they get a generic icon. If that is the case for you. I suggest you try asking in the user support forum. You can access it using the standard "get help" F1 key in Thunderbird.