Not only that, but depending on where it's being delivered to, or what's being delivered, they may put orders on that it cannot be picked up after a failed delivery, and cannot be diverted to another address.
Either get in writing (email) that you will be allowed to pick it up at the Fed-Ex depot if the delivery fails, or ensure you get it delivered to someplace where somebody you know will be there during the day.
There was quite a long thread a couple of weeks ago about people (me included) who have had to do things like take time off of work because there turned out to be no other way to actually get the delivery.