So you’re like one of my co-workers and you never remember to empty your trash. That’s perfectly fine, until Thunderbird starts running a little pokey and then after a few weeks, this pokiness becomes unbearable. In reality, Thunderbird should be able to handle it, but either way, you threw it away, so there’s no reason to save it. So here’s what you do:
Open Thunderbird and go to Tools > Account Settings.
Under the name of your email account, go to Server Settings.
At the bottom of this page, you’ll see a checkbox labeled “Empty Trash on Exit”. Check that box and everytime you close Thunderbird, it will empty your trash for you. It doesn’t do floors or laundry, but there might be an extension…