I guess this is a pretty common e-scam, but it was the first time it occurred at our bank.
A customer is selling something on the web and someone buys it in another country and tells the seller they will wire the money to their account. Instead of wiring the account, the buyer sends a counterfeit cashier's check for 5 times the amount ($50K in our case)by mail for deposit to the customer's account. An unsuspecting teller deposits the check, with a minimum or no hold due to the check's nature. The buyer then informs the seller to wire the excess money back since it was a big mistake. Of course by the time the check comes back, the money is offshore. Luckily we caught it in time.

We just caught one of these, check was drawn on Peninsula Bank in Florida. We told our customer to wait until we could verify the check and when we called Peninsula they confirmed that it was bogus.

We've had some also and we are a small community bank in a rural area so it can happen to anybody.