I mailed two books and both went with DC and both have been received and neither has been deleted or marked as received by the recipient.  I messaged and still no reply or marking of received.

Any ideas?

They don't get removed for that tab when the DC is scanned delivered, they only get removed when the receiver logs on and marks them as received or they go lost in the system at 26 days.

Also being showed as delivered by the DC does not mean it has actually made it to their house. I wouldn't PM people unless the book is about to go lost.  I know I have a book that shows it was delivered to me on Jan 8th and I have yet to see this book.  It shows as delivered when you click on the DC. I don't know where they delivered it but it wasn't to my house.

Sometimes they scan them at the local PO and it still takes a few days to get to the requestor.  Also not everyone has computer access everyday.  If the book goes lost you will receive your credit if you bought the DC through PBS.

I've had the PO 'deliver' a book to me a week before the book has actually arrived at my house.

As the others said, I would wait until the book is about to be declared 'lost' before contacting the recipient, as they might not have seen the book yet, even if the PO has marked it 'delivered.'

I mailed a book DC that says it was delivered just over a week ago.  Pm'd the member yesterday but no answer back yet.

Apparently there is no consistant rule for when USPS scans the DC as delivered.  Some PBS members have them scanned when a book arrives at their local post office, but actual delivery may be several days later.  My post office doesn't scan until it's placed in my mailbox or placed in my hands. 

Some books don't get scanned at all.  I thanked someone for a deal yesterday and she said she was suprised that I had gotten them because the DC never even showed up as being mailed at all. It never said more than "electronic shipping info received" which is what is says when the PBS DC has been purchased but not scanned yet.  She was worried they were going to go lost and that they were still sitting at her local PO. 

Also it's Spring Break time and they might be on vacation.  I just spent a week at the inlaws. I came back to find 10 books had arrived.