My Poor Mailbox

When James and I woke from our nap I looked outside and saw my mailbox was gone. I went out to investigate and the mailbox post was ripped out and laying on the ground, the mailbox itself laying about 10 feet away in the drainage ditch. There is a big chunk taken out of the wood too.

What the hell is going on with my mailbox? I've lived here 6, maybe 7 years and never had any problems until this year, when it's been knocked down twice so far. I think I know who did it, but I don't have any proof. The Avon delivery truck stopped by and left a box. I saw him pulling out of the driveway but I didn't watch him all the way. No one was working across the street, so it wasn't them. Luckily it only cost me $5.00 to fix this time, the mailbox wasn't crushed like last time.