I will ship my cards in penny sleeves in toploaders. Neither I nor anyone I know has ever had a problem with regular envelopes, so that is how I ship unless the trade value is over $40. If it is over $40 I will send in a bubble mailer with delivery confirmation and will expect the same.

Also, if you are checking for legitimacy, go to my friends. gtcooke94 is my brother, and he is +29 if that makes you feel better about my low number of completed mail trades.