Save tracked delivery proof for USPS tracked orders, as numbers are recycled
Because USPS recycles tracking numbers more frequently now, when looking up a tracking for a claim USPS has already recycled the number - which some scammers use to their advantage. If upon delivery a screenshot of something we could use as proof of delivery was saved in the sale file, it would help for those times when months later a customer claims something wasn't delivered but the number was recycled.
Diego Ramirez Cirkul, Inc. commented
If you still have the order in Shipstation you can hover over the "delivered check mark" and see the previous delivery confirmation email.
If you are sure it is a scammer that should be enough to suffice them!