Does anything happen? I have a few books with DC that were sent out weeks ago, so I have the credits for them already. One went to an APO somewhere overseas that I can't track. They have all been scanned and marked as delivered. What if the people that received them just never log back onto the site to mark them as received? Will it affect my account in any way, and how long will they remain on my "Books I've Mailed" tab?

The system will automatically cancel the transactions if they are not marked as Received 26 days after they were marked mailed (35 days for the APO book).  They will be recorded in the system as "Lost in the Mail" because even though a Delivery Confirmation confirms delivery SOMEWHERE, there is no guarantee that they were delivered to the final destination appropriately. 

Since you paid for PBS DC, you will not lose a credit for them (PBS Postage services guarantee your credit in the event a Sent book goes "Lost").  However, if you hadn't, without PBS postage, the credit would return to the Requestor and the Sender would lose out on receiving a credit. 

Note that the system keeps track of books that go "Lost" and Requestors with a habit of not marking their books as Received could be sanctioned by the site and/or lose their PBS account.

The APO books that I've sent weren't scanned when they were delivered; the last scan was before they left the US.  Eventually they did reach their destination, but in the meantime they went lost and moved to my transaction archive.  When the requester receives your book, they can mark it received from their transaction archive if it has gone lost and therefore is no longer on the "en route to me" tab.

For a variety of reasons, the PO occasionally marks books delivered before they are actually delivered.  And sometimes people forget to mark the books received, or they've been out of town for a few days, etc.   I use PBS postage also, and when the details show that a book has been delivered, I wait a week or so and then PM the requester.  My theory is that if the book has not actually been delivered, it's time to start the search.  So far, the books I've sent have all eventually been mark received. 

I have a good story for this:

A friend of mine posted a WL book to me.  USPS DC showed it delivered on January 15.  I checked the PO and it wasn't there.  I took the tracking # in and they confirmed having seen it (I have a TEENY post office) the day before.  We waited over the weekend, and on Monday they searched the package lockers and PO boxes, it wasn't there. 

So we waited, hoping that someone would put it back in the collection bin so it could be delivered to ME.  On February 18, the package was turned in opened.  The person who received the book was apparently a little offended by the cover as the book was wrapped in rainbow paper (not how it was sent to me).  I have no idea why they kept the book for over a month before turning it back in.  It wasn't mainstream fiction by any means.

In the meantime PBS marked the book lost.  When I got home the PO, I went to my TA and marked it received so that the sender would get her credit.

So don't give up! 

Just wanted to point out that if you PBS DC and get your credit, you should still do a little follow up if the book is scanned delivered. From the Help Center:

If you sent the book with Delivery Confirmation and it has been recorded as delivered by USPS but hasn't been marked received yet:

• Remember that the book could have been scanned as "delivered" at the local PO, before it went to the requestor's mailbox--the actual delivery can be a few days later  Also, the book could have been misdelivered.
• You should FIRST contact the requestor using the button on the transaction on the Books I've Mailed tab in My Account when a few days have passed after delivery.
• If the requestor does not respond to your PM within a week, and has not marked the book received by a week after the delivery scan, contact us.  We will look into it.
• If you used DC purchased through PBS, or PBS Printed postage, you will already have gotten your credit for sending the book.

Thanks for the info. I guess I'll wait a couple more days, then start contacting people. As far as the APO, it was scanned once it reached the other side of the Atlantic (after three weeks), but this is all I've gotten so far:

Delivery Confirmation Events

USPS DC#: 420094649102805213907311342627

• 2/27/2010 9:40 AM - Electronic Shipping Info Received - PHILADELPHIA,PA
• 3/1/2010 1:43 PM - Acceptance - PHILADELPHIA,PA
• 3/23/2010 7:23 AM - Arrival at Unit - APO,AE

Also, if the requestor hasn't logged on in a while, the system will mark a book "received" instead of "lost."  I'm sure an e-mail is sent out first asking them to log on.