Nope, not according to the post office.Originally Posted by amma
I mail a lot of books and would not put any but the thinnest in a manila envelope. I use poly mailers that I buy in bulk on ebay. (they are cheaper than Tyvek).
You can get $.19 Delivery Confirmation with Media Mail if you print postage from Paypal. Unfortunately you can not print MM postage on the USPS website.