What if the sender agrees to send the book, but doesn't mark it mailed before the deadline?

• If there is another copy of the book available, your request will automaticlally be passed along to a new sender. 
  • You will not get an email notifying you if this happens.
• If there is not another copy of the book available, the request will be canceled, you will get your credit back, and the book will go onto your Wish List. 
  • You will get an email notifying you if this happens.

More Questions:

What happens after you submit a request for a book
What if the sender does not respond to my request within 4 days?
What if I want to cancel a request I made?
What if the sender is taking too long to respond? Can I cancel and reorder from someone else?
How can I tell who's sending me a book? (or to whom I am sending a book?)
When will I get my book?
What are the differences between the Reminder List and the Wish List?
Box-O-Books Tutorial Step 4: Boxer Negotiation
What is the Wish List?
How the Wish List Works