Pre-parse isn't stopping a loop

[Sapro]

Loops are thus far the most frustrating issue I am experiencing. Here's the "loop of the day" that I can't seem to stop:

1) Staff sends email request to vendor.
2) Vendor system auto replies - but strips the [ticket#] out of the subject
3) System creates a new ticket and sends auto-notification
4) See step 2.

Staff needs the confirmation - but only needs it once. Since the [ticket#] is stripped out, we have to merge the newly created ticket with the old one. Annoying but not a huge problem.

SO I built a parsing rule as such:

Stop Processing Rule: Yes
Execution Order: 3 (2 other 'loop' rules above it that do not apply to this type of loop)

Criteria:
Subject - Equal - Exact subject being sent from vendor
Email Address - Equal - Exact sender's email address
Match ALL criteria

Reply to: blank
Forward to: blank
Ignore: No (remember my staff wants the response as confirmation)
Do Not Send Auto Notifcation: Yes
Do Not Process Ticket Alerts: Yes
Do Not Parse As Ticket Reply: No

... What is wrong with this rule? It keeps looping and I would have thought the "Do not send auto notification" would have stopped it??