(Using Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0rc1) Gecko/20020417) Set mail preferences to BCC to yourself when sending a message. Create a new message, then save it as a draft. Open the saved message in the draft folder in order to edit it. A new BCC is added - surely there should only be one? - otherwise multiple edit/saves result in many BCC's to yourself.
*** This bug has been marked as a duplicate of 140913 ***
verified dup of a dup.