How can I delete emails that only appear when I do a spotlight search?

I have a number of emails that are only locatable through a spotlight search which I am unable to delete. They all appear to be unread, although they were read. The only options I have when I bring them up are to "Cancel" or "Send". Choosing "Cancel" brings me to whichever email account I was most recently using. Hitting "Send" does, indeed, send them, but makes them no easier to delete.