If you’re selling something online beware of fake payment scams.
When you use an online platform to accept payments (PayPal is the most common), you generally will get some kind of notification when the funds show up in your account. Fake payment scammers will purchase an item, then create a email message designed to trick you into believing that an actual payment has been made. They may use graphics and text from actual, legitimate messages, and many will spoof the sender address to make it more realistic.
If you simply trust this email message without logging in directly to check your account and verify that payment has been made, you might send the item without having been paid for it at all.
In some cases, the scammer will also send you a message claiming they received confirmation and asking you to check your junk/spam folder for yours. This is a ploy to trick you into viewing the fake confirmation email, as many spam filters will flag them as suspicious.
The key to avoid this type of fraud has already been hinted at: never trust a confirmation email on its own. If a buyer claims to have sent a payment, login to your account and verify it with your own eyes. Contact the service’s support if you think the payment was legitimate but hasn’t shown up yet.
On a related note, as soon as a buyer tells you to check your junk or spam folder for the confirmation email, that’s a major red flag. And as always, never go off-platform (switching to direct text messages, for example) on any online transaction.