When I get a money order I wait a few days after cashing it before I ship, just to make sure it doesn't come back as a fraud. I always ask one of the bankers behind the desk how to protect myself. The one at the desk not the counter. Even after cashing the MO can still come back as fraud and they will deduct it from your acct. I just don't know enough about convenience store money orders
In all my listings I now state either paypal or a postal money order anything else I send back. I've sold things over the limit of a postal MO and I just tell them to get two.