The Postman Pig is a Medium Pig found when the pause button at any level is clicked/tapped. He shows ads about updates of Rovio games when the level currently played is paused. When tapped or clicked on when happy, he feels sad and a rain cloud appears above him. When tapped or clicked, he starts to feel sad with his bag closed and the updates disappear, but if tapped again, he feels happy, the bag opens and the updates reappear.
He did not appear in the version 2.0.0 & version 2.0.2 of Angry Birds, he returned in version 2.1.0, but then disappeared again, and is currently available only in the online version of Angry Birds Friends! (Which currently only shows the Power-Ups poster) and in messages of Angry Birds 2. The Mechanic Pig slightly resembles him. Unlike the other pigs, Postman Pig doesn't appear as an enemy to the birds and is just a mailman.
There is a plush toy of the Postman Pig.
The Postman Pig may be friends with the birds, as he is the only pig that has nothing to do with the eggs being stolen and doesn't appear as an enemy in a level. Either that, or he's just a neutral character.
He looks similar to the Mechanic Pig in Bad Piggies, the only difference being Mechanic Pig's hat only covers his left ear, whereas the Postman Pig's hat covers his whole head but in Angry Birds Friends he only covers his right ear on pause ads.
Postman Pig does not appear in the pause ads anymore, but he still appears on the pause ad of Angry Birds Friends.
A pig that resembles the Postman Pig, with the updated Toons design as well as slightly updated hat and sack, has recently appeared in a message in regards to Clan Events streaks in Angry Birds 2.
He even helps the player by giving rewards and news; since the Postman Pig from the classic game gave a hint to find a Golden Egg and ads to the games, the willingness of this current Postman Pig in helping you instead of his own kind implies that it may be the same.
Postman Pig happy.
Postman Pig happy. (old look)
Postman Pig with his newsletters missing. (old look)
Postman Pig happy. (Facebook version)
Postman Pig with his newsletters missing. (Facebook version)