http://5rzkisd745el4yr7krh5qc4f5sgblvg4i5qtuxivfgxcxtr65ejd7gyd.onion/help
If it is on: it is sent on a fixed half-hourly clock, never at the moment of a sale , and its contents are the fixed words “New activity — check the shop” with no amount, no item, no order id and no count. It goes out over Tor like everything else. So it can reveal that something happened somewhere in a thirty-minute window, and nothing else — not what, not how much, not whose.