If the mail by date passes.....let PBS work and do not cancel it.  The request will be passed onto the next person  who has the book. What might happen/did happen is the person mailed it, but forgot/didn't mark it mailed. So you might end up  with it anyway.

The sender has a two day grace period. It sounds like you're still in that window. If the book isn't marked mailed by then, it will either go on your wish list or the request will be forwarded on to the next person who posted the book.

I have been a member for over a year and never had this happen thank goodness. But what I would do is contact the person by using the PM button. Just write them and let them know the "will mail by" date has passed and you were wondering if they forgot to mark it mailed. I always try to play dumb so the person won't think I'm being rude or mean.

Ashley