How can I get rid of downloaded emails that are stuck in POPcon's queue?

POPcon keeps downloaded but not forwarded emails in individual *.msg files in the Program Files\POPcon folder. Just remove those *.msg files that you don't want POPcon to forward to Exchange - POPcon will detect the removal and delete the mail from it's queue.

If you just move the files to another folder instead of deleting them you can have Exchange attempt delivery again by moving these files into the PICKUP folder (inside the POPcon program folder).