Why do dogs bark at the postman?
It’s a game that the dog always wins and is reinforced for every time it occurs. The mailman comes to deliver mail at your home. The dog barks to alert everyone that there is a potential intruder. The mailman leaves, and the dog apparently perceives he has successfully chased the mailman off. One way to curb this is by having the mailman give your dog treats. Your dog may still bark out of excitement.