The publisher, owned by media mogul Rupert Murdoch, quickly apologised for the hacking incident in a follow-up alert and on Twitter.
"Our push alert notification system was compromised this evening. We are working to resolve the issue. Please accept our apologies,” the publisher wrote.
The push alert system for our mobile app was compromised this evening. Please accept our apologies.
— New York Post (@nypost) April 2, 2017
One hacked alert read: "Heil President Donald Trump”, while others appeared to be more elusive religious references and song lyrics.
"Open your heart to those you do not understand and listen to all those you fear and look down upon,” one message read.
Another alert included lyrics from Nirvana's song Come As You Are: "Take your time, hurry up, the choice is yours, but dont be late..."