I’ve read about this. They basically reverse engineered how USPS creates the unique tracking number.

They aren't hard to generate. They give you how to generate them via their own documentation. It's just made up of an app ID, service type code, mailer ID, serial number, and check digit.

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devy 37 minutes ago | parent [-]

No. That won't work. Every carrier has it own way to generate tracking number. And that number must have registered in the carrier's database before it becomes "valid/sanctioned".

If you generate a random number even fitting the pattern and looks like a real one, the scan will fail with an error and fail to register tracking information every single step of the way that package gets scanned from dropoff at the retail postal office (this was the case) as bulk inbound pickup from USPS are only allowed for USPS verified partners.

Label creation (which generates the tracking number) is a billable action in their API. Some volume partners have pre-arranged/allocated tracking number segments assigned to the bulk volume partner/shipper (similar like how IP address v4 is assignment from IANA). And that pre-allocation tracking number range requires $$$$ contract in place. Billing that is post paid like cellphone bill.

Most retail shipping software (like shipengine, pirateship etc.) bills using the prepaid method, meaning you will have to pay for the label at the time label is generated.

Disclaimer: I used to work for a carrier that integrated a few dozens of global shipping carriers.

	▲	theturtletalks 13 minutes ago \| parent [-]
		Yes, I’m deep in e-commerce and fraudulent labels are all over the place. Even Amazon, 3rd party sellers are using these fake labels to sell items for cheaper and win the buy box. Even UPS has this issue. I get that they have reverse engineered how the numbers are created, but how are they showing up in USPS and UPS databases? Are shipping platforms like shipengine getting these labels pre-made and this fake label seller has reverse engineered how these tracking numbers are created programmatically and are essentially using the ones allocated to these big shipping platforms?