Which “art project” started off with these 3 postcards?

Bonus question for today. What is blacked out?

Cracked by: shrik(2) , Shwetha Maiya(2) , udupendra(2) , Manish Achuth(2) , Sumanth Patlolla(2) , rohanquizzer(2) , shrey , aditthya(2) , Debasish(2) , raklodramA(2) , krudebox(2) , varun , Siddarth Pai(2) , jowens(2) , Riyaz Usman(2) , Rogi(2) , Raghuvansh(2) , dineshk(2) , Ananth(2) , Anjul(2) , Jins(2) , Thejas V R(2) , Moju21 , vinayaknp , Dibyo and Qqsachin

Answer:

PostSecret
Bonus: Portal