If you use the paypal link in your invoice to pay for your order then your order number is automatically attached to the payment notice that we receive. If for whatever reason you choose not to use that link — which is fine, you can pay for your order however you’d like — just please be sure that you include your order number on the paypal reference line or if you pay by check or money order then write the order number on the memo line. We’re processing dozens of payments a day and there are at least a few payments received every day that reference no order number and often the names and/or email addresses attached to the payments are not the same as those attached to the order … a wife’s paypal account pays for a husband’s order, or vice versa, or a father’s account for a daughter, or a roommates’ for a roommate, etc. When that happens we have to drop into to detective mode and to determine to what order the payment should be applied. Being sure that your order number is affixed somewhere to your payment will help us out tremendously.