Gmail is smart at a lot of things. Turns out, it can detect receipts that you receive in email. Gmail can locate receipts from Amazon, Google Play or similar services. This feature is powered by the Smart Label experiment from Gmail Labs, but you don’t need to enable that experiment.
Receipts from PayPal, Google Play and Google Checkout, order confirmations from eBay, Amazon and other shopping sites were detected by Gmail, Google System writes.
How To Search for Receipts in Gmail
Here is what you need to enter. label:^smartlabel_receipt.If you type in just that, Gmail will list all the receipts that it could find. But you can look for something specific, say a book name or a movie name adding it after this piece of text.
Easy and useful!