[otrs] Junk Bin Deletion: Bug Or Feature?

I've been playing again. :) I set up the junk folder to delete our junk mail when GenericAgent runs. While messing around with that I was looking through some older closed tickets and noticed the Queue dropdown was still active... so out of curiousity I dropped one of our first test cases in there and sure enough, it was deleted on the next pass. So my question. Is that supposed to happen, and when it does, what happens to the associated message thread? Is this a hole in OTRS that allows you to accidentally wipe out the originating message, or is the system set up where all child elements of a thread are removed when GenericAgent makes it's pass? Charles