The Post Office will cash the money order if they have enough funds on hand and the mo is legit.. . Be aware that there are a huge number of fraudulent money orders out there and cashing fake money orders is one of the hottest scams. The tell tale signs of the scam is if someone asks that you cash the money order and send them part of the money with a legitimate money order or check. If this is the case , not only will you lose your money but you might be prosecuted as a part of a money order fraud/money laundering scheme.