Man hits arm with bat mail slot
It sounds like you're describing a rather unusual and potentially humorous situation!
So, to clarify, a man hit his arm with a bat that was inserted into a mail slot? That's quite an... creative way to get hurt, I suppose!
Can you tell me more about what happened? Was the man trying to retrieve something from the mail slot, or was he just having a bit of fun? And did he get hurt badly, or was it just a minor injury?