I just received a book that has a stamp on it that says "POSTAGE DUE_______"   but there isn't an amount written in,  and the book is in my mailbox already.   

The stamps on it total $1.76,  and the package weighs 6.4 oz.  When I checked on usps.com,  the cost for First Class is $2.24.   So definitely there isn't enough postage on this baby. 

My questions are:    (and please forgive my ignorance on this matter)

Am I going to get a bill in the mail for 48 cents from the USPS?    

Since it was sent First Class mail,  the USPS eats the difference OR do they bill the sender for the balance?  

I've read in this forum about people going to pick up a package at the post office and having to pay the balance,  but I know that this is only for books sent by Media Mail.

Another question while I am thinking about this:    

I haven't marked the book received yet,   so how should this be handled?    Everything is fine with the book, so no need for a RWAP at all.    Should I just send a note to the sender letting her know that there wasn't enough postage,  and let PBS know as well in the comment section?  

Thanks for your help!   :) 

IMO, you have a nice mailman who was doing you a favor. I think he nicely just put it in your box (or mistakenly put it in your box! lol) 

Usually they would have knocked on your door and asked you for the postage due and if you're not home they would have taken it back to the post office for you to pick up. 

At least that's what has been my experience. 

I'd check with your mailman next time you see him. I wouldn't go to the post office cuz I wouldn't want to get my mail man in trouble if he was doing me a favor. 

ETA: I would probably shoot the person a pleasant PM that mentioned the postage deficiency. If it was stamps, some could have fallen off (usually sticky residue would be left behind but not always). 

I would send them a quick PM about it. When I was new here I just stuck stamps on the books that were similar in size to books I received with stamps on them. I figured I couldn't go wrong if I used the same amount of stamps on a small paperback. Anyway, it finally caught up to me when a member let me know that they had to pay thirtysome cents in extra postage. They were very nice about it and I was glad they gave me the heads up so I could correct my methods. As long as you're nice then I don't think it should be a problem. I was very glad it happened to me with a nice and understanding member. I'm sure they'll feel the same about you. :)

Susan - thank you so much for the feedback - it is very much appreciated! :)  

I checked the PBS help docs, and the last line says that sometimes (though very rarely) the post office overlooks a postage due item and does deliver it.  So this is probably a case of that,  or my postman is super nice and delivered it anyway :)   So glad we gave a Christmas card w/ tip to our postal guy -- he really has been awesome and is such a nice guy. 

I will pm the sender just for a heads up, and make a comment to PBS for an FYI.   There isn't any residue on the package,  I checked.  It doesn't look like any stamps fell off in transit.  

Thanks again! 

Amee -  I pmd her to let her know.  :)   Looking closer at the wrapper,  it has DC and the postal price is clearly printed on the wrapper where the stamps should be (i can see through the stamps on the side).   It says $2.07 postage and 19 cents DC - total $2.26.   Maybe a stamp did fall off,  but it really doesn't look like it.  I'll wait and see when she replies.    I guess she didn't take it into the PO to drop it off and have it scanned there,  she must have just dropped it in a blue box.   who knows :)