Cause
The problem is that the Requestor has an auto-responder on his/her email account which is STRIPPING out our Email Subject line which includes the necessary [Ticket #xxxxxx].
Effectively, as a result, his/her auto-response would be seen by the system as a NEW email and send off an Open Confirmation Email, to which her auto-response would do the same again, and another case is created - This cycle then repeats over and over.
Note: To stop email looping permentently please refer to the following link: http://www.versadev.com/kbview.aspx?kbaid=209
Resolution
(1) Temporarily pause (uncheck the necessary check-box) the Open Confirmation Email being sent out of the Queue to stop the 'ping-pong' of case creation (then turn it back on after a window of 15-20 mins).
(2) Set the offending generated cases to a status of "Dead" (trashed).
(3) Created a Routing Rule in the system with a lookout for this Requestors email address stating that if a future request comes in from this person, then an Open Confirmation Email will not be sent to this person.
Note: Steps 2 and 3 are optional and may not be necessary, however it is our recommendation so as to avoid the problem re-occuring.