Selecting multiple emails in the Trash folder then clicking the "Delete" button doesn't actually delete them, even though they seem to disappear. This has already been reported in the feedback thread.
You can of course delete the emails individually.
But with a few clicks you can create a sub-folder in Trash, select all the duplicated email reminders or whatever in Trash, move them to the sub-folder then delete it.
Confirm the deletion when you get the warning box, and all the stuff you didn't want and didn't ask for is now gone.
