yesterday
We are a large publishing house and use a Bound Printed Matter permit with USPS. In the past we have created a custom label in wordpress to do this. It would populate the customers address and our return address and our BPM permit number would appear like a stamp. It is a pretty simple straightforward and I have provided a image example of what the label should look like.
No postage needs to be purchased. USPS draws from our customer account when processing our BPM.
Thank you.