If you use the My Guelph site to sell items and you recieve an email from someone who wants to send you a cashier's cheque for more than your asking for the item you have for sale and have you mail them the difference DO NOT agree to do so. This is a common net based scam where the cheque you recieve is fake and by the time you figure this out they already have your hard earned money and it's too late. The only way to stop these scammers is awareness! Don't be fooled!