Got this one in the mail the other day. Somehow an eBay dealer thinks they need to send a stamp via Certified Mail. Fortunately I was home and just had to sign for it. Otherwise it would have been my wife or I heading to the PO by the end of their day, which would be a mad rush.
But I admired the stamps used for franking and the fact that they arrived without the usual tears from the sorting machine and with cancels.
So.. I flip it over and what do I find... the motherlode of fractionals!
I use service inscribed stamps regularly, have been for 30 years, and have never ever put a permit number on a single envelope. Have never had a problem with the envelopes either being accepted by the postal clerk or with the envelope being delivered to its intended recipient.
"He also used precancels without posting his permit number on the envelope."
It's not necessary to include one's permit number (it does help, however, with some postal clerks who may not know the rule). But, such stamps need to be on the front of the envelope, and the envelope needs to be marked at the top "FIRST CLASS MAIL".
I do not believe that these stamps are authorized for payment of certified mail service, or any others service other than first class postage costs. I don't know how much the envelope weighed. You could figure out if the total face value of the fractionals only covered the first class postage portion of the total postage costs. If there was any overage that went to pay for the certified service, then you should have received this envelope with postage due that would have been assessed by the receiving post office. That would have added even more to the cover if USPS added ancillary markings of that information to the cover!
I would keep this cover intact. At the least you have an improper use of service inscribed postage stamps.