I rescued an 8-yr-old dog about 1 month ago. He destroys the house when I'm gone. Should I crate him or is he too old?

Hello,

I rescued and 8 yr old Akita from the animal shelter about a month ago. The first week was perfect and he was a great dog. After that, he has started to tear down my vertical blinds in my front picture window. I believe it is due to the mailman walking in front of it to get to the next house. In the process he has also knocked over an antique lamp which was my grandmother's and broke it. That was my fault though for not moving it. I am trying different things to prevent this behavior, I tried to enclose him in my kitchen but he gnawed at the door frames trying to get out so that just backfired on me. I put the stay off spray on my blinds and that has seemed to work somewhat, he has only pulled down one since then, but has started to pull down the side window blinds in an attempt to get to the side of the house. I am only guessing that it is the mailman. I go home for lunch about 3 times a week, I can't get home every day though. All of the damage occurs after my lunch though so I can only assume it is the mailman he is after. I have thought about crating him but was not sure if this is the appropriate thing to do, is it too late since he is 8 yrs old already? Are there other alternatives I can use to curb this behavior?

Mark