When you make an order for a small item and select standard shipping, your order will most likely ship by US Postal Service (USPS) First Class Mail. Letters and bill payments that you mail go by First Class.
The USPS has a classification for commercial shippers called First Class Parcel, which is what we use. We want to have ALL orders that we ship be trackable, and First Class Parcel mailing allows us to use USPS Delivery Confirmation for tracking.
Deep within the USPS rules are definitions about what can and cannot be a First Class Parcel, and one of the rules is that the package has to be at least 3/4″ thick. Even if we pay the extra cost for Delivery Confirmation, the package cannot be sent as a First Class Parcel if it does not meet USPS rules.
When we first started shipping using our current system, we would sometimes have a package returned, or a customer would be asked to pay postage due. Most of our ‘flat’ First Class Parcels made it through the mail ok, but in a few cases those eagle-eyed postal employees spotted our too-flat mail pieces and tagged them.
So now when we ship using First Class Parcel, and we ship using a bag or an envelope, and the package looks too thin, we add in a little foam thickener to make sure the package meets USPS requirements for First Class Parcels.
It seems silly to have to do this, and we would like the USPS to change this requirement, but don’t expect them to. It would make too much sense to do that.