I'm not positive, but I think it does go "lost" if the requester doesn't mark it received.....I'm pretty sure, tho

Yes.

Mindy, that's a very interesting question and I don't know the answer to that one.  The Help Center says to contact TPTB if it has not been marked received after a week of showing the book was delivered by delivery confirmation.  I would PM the receiver and gently remind them to mark the received if she has received it.  Something may have come up and they are out of town or it might have gotten delivered to the wrong address.  But I would try and contact them first, before contacting PBS.

I agree with Hunter. When I see that a book has been delivered, I wait a couple of days and then just send a very nice friendly PM asking them to please mark the book received.  I've never had someone who didn't mark it after the reminder.

I always try to mark my books the same day I get them.  However, I have a terrible PO.  It loses mail and sits on mail and does all kinds of things including sending mail back before they ever tried to deliver it.  Not much I can do about it.  I only hope my outgoing mail is treated better than the incoming mail.  When it's incoming I imagine that a person designated to do so marks them.  That doesn't mean the carrier gets it soon.  I'm constantly amazed at the things post offices can do.  And the things they can't.

Ruth

I usually wait five business days then send a polite PM to the member, explain that DC is showing the book as delivered and asking if there is any problem.  The tone I try to convey in my PM is, "If there's something wrong with the book, tell me and I'm sure we can work it out agreeably."

Generally I get a response back along the lines of, "Opps!  Sorry about that!" or, "I thought I marked it", "I was away from home", etc.

PM sent and book marked recieved :)  Thanks for all the advice.