Is there an option that previews, as opposed to opens, the next email after deleting an email?
or... just to avoid the Delete Folder,
Make a new folder called 'UPS mail', and set a rule to move all email with UPS notification, or whatever the key wording is, to that location. When you download, all the bad stuff should go to the special folder, leaving normal emails to be viewed as normal. You can then empty the folder as you wish.
Similar to what you have tried, but slightly different. Let us know.