"We would love to produce all designs submitted, however Z***** prides itself on upholding all intellectual property rights as well as our own content guidelines and copyright policies. In this instance, your order contained products with copyright-protected content related to US postage Stamps, which Z***** is not currently licensed to produce on merchandise whether or not it is a real postage stamp. Your order has been cancelled in full."
The above came in response to my attempt to produce a business card with an on-line custom printing company using one of my fictitious postage stamps as a design element (El Capitan 5¢). After the rejection, I wrote back to them pleading my case informing them that I am in fact the holder of the copyright and that the stamp is entirely a creation of my imagination. There never has been a U.S. Postage stamps like this one, and likely never will be. I implored them to reinstate the order as designed. Again it was rejected. Two more times.
Finally I called their customer service number to speak with someone from the design review team asking exactly which copyright was being violated. Was it the stamp shape, with a perforated edge? Was it the words USA? 5¢? El Capitan? The increasingly flustered rep could only say that my work looked like a stamp, and that postage stamps couldn't be printed, period.
I'm tempted to submit my design again, this time with a stamp that is completely black, with no text, then incrementally submit orders that gradually add text and imagery, just to see at what point the copyright violation panic is triggered.