It's a nightmare.
Our company uses CourierPost, and we are now dealing with hundreds of emails from customers asking where their stuff is.
Most of the time, we don't know - it's in CourierPosts black hole somewhere, and their tracking hasn't been updated since they collected it from us (some of it up to 3 weeks ago). It does look like a lot of the items we sent out this week have been delivered, but anything sent in the 2-3 weeks prior are stuck somewhere.
Everyone looks bad in this situation.