I absolutely agree with @Sajhafan,
USPS sucks big times..
I've sent some mail in the past.. it never got to the destination.
I just sent a mail just a few weeks ago, I made sure it gets to the destination and it seems like someone has not got my mail yet for that day. I went back to the USPS and it seems they lost it.
It happened to me when receiving package as big as printer toners which is like about 2 feet in width. I was so upset and I thought they lost it. It took frigging 4 days to get my package, it was not even a small envelope it was damn big printer toner with tracking number. 
Their site said 'delivered' but I never got it. They didn't even tell me what the heck happened.
I will never ever use their service in my life.