Shape of Things to Come

The first step is to make every effort to design your piece so it can be categorized as a letter. Of course, there are additional physical criteria that must be met for total USPS automation compatibility. But you should worry about the issues (and costs) of tabbing, folding, sealing, spot gluing, etc., after you have paid attention to size and shape and identified the postage incentives for your mail class. Then you can determine if meeting the additional criteria for total mail piece automation-compatibility is worth pursuing.