Netflix posted the following notice on the top of the website (you have to click to see the entire message):
IMPORTANT: Your DVD shipments might be delayed… We're sorry to report that we've been experiencing issues with our shipping system, so some of you are not receiving DVDs in a timely manner and some of you have not received emails letting you know we got a DVD back from you.
We apologize and we'll be automatically issuing credits to all of you whose shipments have been delayed. Our goal is to ship DVDs as soon as possible and to provide a personalized email update to you if your DVD shipment was delayed.
We're sorry for any inconvenience we've caused you and thank you for your patience.
The Netflix Team