USPS Media is the cheapest way to ship educational material. However, it has some drawbacks, not the least of which is in its reliability and delivery speed. Media mail is reserved for educational material only; as such USPS reserves the right to inspect media mail packages they receive as they see fit. This means opening the package and inspecting the contents. Often times they will firmly re-secure it and ship the package without incident; however, there are incidents in which the packaging or product may be damaged by these inspections, leading to damaged product delivery or a lost item.
Another key thing to remember with Media Mail is that USPS places certain priorities on packages based on the delivery method. Media Mail sits firmly at the bottom of this priority list. If USPS is only able to fit a certain amount of packages on the truck, media mail will be added last, if at all. This may cause delays in the shipping of your product to your customers. This issue will only increase closer to holidays, especially in the 4th quarter where many packages will be getting delivered as more people use faster shipping options. The carrier's truck will quickly fill up with priority packages, which if they are gifts, may also be larger packages. Leading to less room for Media Mail packages, causing further delays.
Return postage fee:
All insured First-Class Mail, First-Class Package Service — Retail, First-Class Package Service — Commercial, and Priority Mail, pieces are forwarded and returned at no additional charge. Since Media Mail is not insured, a return postage fee will be charged, if your package is returned.