Misusing USPS Priority Mail supplies is serious business. There are often discussions on the eBay Community Packaging and Shipping board about this topic. On one hand, the USPS blatantly advertises, "If it fits, it ships." On the other hand, the eBay customer gets the final word on the packaging job, and she may not like a designer handbag or a pair of designer jeans shoved into a flat rate mailer. So what is an eBay seller to do? Sellers want to offer the most economical shipping cost to their buyers, but sometimes the USPS doesn't stand by their advertising.
Several sellers on the eBay Community Packaging and Shipping board have reported that the USPS is not accepting flat rate envelopes (FREs) for merchandise, as they state FREs are intended for documents. Clerks are measuring the FREs and if thicker than 1/2 inch, rejecting the package. The official word, from this page on the USPS website, states:
1.5 Flat Rate Envelopes and Boxes
"Any amount of material (up to 70 pounds) may be mailed in a USPS-produced Priority Mail Flat Rate Envelope or Flat Rate Box. When sealing a Flat Rate Envelope or Flat Rate Box, the container flaps must be able to close within the normal folds. Tape may be applied to the flaps and seams to reinforce the container, provided the design of the container is not enlarged by opening the sides and the container is not reconstructed in any way."
In other words, if it fits, it ships. But the envelope must close securely on its own and not be a jumble or tape, staples, or other material to hold the package together. This may be an issue of postal clerks making up their own rules, because clearly they are not seeing what comes in the back door. eBay sellers have been using FREs for years and shipping all sorts of things in them with no problems.
If you are an eBay seller encountering an uncooperative clerk, print out the statement above from the USPS website and keep the printout with you. If a postal clerk refuses a FRE, show them the information from the website. If the clerk still won't accept the package, ask to speak to a manager and show the manager the official statement.