21. Sellers –– Do not post items for sale that you do not have in your possession. Also, do not list items for sale unless you are 100% positive that you wish to sell them –– no "testing the waters" to gauge buyer interest or taking pre-orders. No sales for third parties. If your "friend" wishes to sell here, he must take the time to open a separate account. Refrain from posting personal info in ads, such as phone numbers and email addresses.