The way online trading works is generally based on a system of trust, but there are ways to be more sure that a person is trustworthy. First, if the person is an experienced online trader, they will most likely have a list of references that you can check out. Also, if someone does take all your best cards you don't have to just sit back and take it. If the other person doesn't send you the cards, it is considered mail fraud since the trade has to be done through the postal service. Because of this, if you save all your emails, you can file charges against someone who trys to steal your cards. These charges are quite serious, and can result in large fines and jail time. For more information on online trading, go to MOTL(www.magictraders.com) everything you need to know about online trading is there.