Can be done.
Account -> Properties -> Mail management -> enable 'Delete messages from server when it is removed from Trash'
It only works when you don't move messages from the receiving account: when moved to a different account or to a common folder, the link with the original account is gone.
Most likely it won't work either when you're using folders on the server to sort your mail for web mail as the pop3 protocol doesn't support folders.
Note that when it works, the messages won't be deleted from the server when yopu move them from trash, but thgey will be deleted from server the first time TB checks your server after you've moved the messages from Trash.
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I'm just a user of The Bat! I don't work for Ritlabs.