This is probably a pretty silly question but I have never been sure about the answer.
If you drop mail off at the drive up mail boxes at a post office, the mail boxes are usually labeled “stamped mail only” and “metered mail only”. I know that metered mail refers to mail sent out by businesses which use a machine to weigh and print the correct postage.
What about business reply mail? These don’t seem to be technically metered as they just have a First Class permit number. Which mail box should I use? I trust the post office to handle it properly either way, but I guess I am anal enough to worry about using the proper mail box.
And just to make this more interesting, here is a bonus question.
I don’t recall the permit numbers on business reply mail to usually be more than three digits. How is the billing done for business reply mail since there must be a lot of duplicate permit numbers. I am guessing it is a combination of address and permit number?
I don’t work for the Post Office, so this is just my WAG for whatever it’s worth.
I’m assuming the reason for separating stamped and metered mail is that the metered mail doesn’t have to be postmark stamped. Therefore I would guess the business reply mail would go with metered.
I think the permit numbers are issued by the local Post Office, and not by a national registry, so the number would be unique within the city where it was issued.
I suppose the greater question would be what happens to a piece of stamped mail that get dropped into the metered-only box, and vice-versa. I suspect for either case, a postal clerk, or more likely, the facer-canceller (the machine that does the postmarking) kicks it out.
Keep in mind that a lot of mailboxes are mixed - people drop stamped mail, reply cards and metered mail into them - and it all gets there. The Postal Service really is amazing in its ability to transport however many million things across the country for 37 cents each in just a couple days.
Homework assignment for the OP - the next time you have a business reply item, go into the post office and ask the clerk which box is preferred.
FWIW, I asked once and was told to put anything that is not actually metered in the “stamped mail” slot, specifically including those “postage will be paid by addressee” envelopes.
A quick call to my sister’s boyfriend, a 23 year USPS employee, he says it depends if it has the routing bar code on the face of the envelope or card. Those with the bar code can go with the metered mail, those without should go with the stamped mail.