Delta Flight 17 Mumbai to Atlanta

[sam14]

My mom is flying from MUmbai to Atlanta on a direct flight. But I recently found out that the Flight stops on JFK airport at New York for about 2 hours.
Where does the customs and immigration for this flight happen?
Delta tells me that it is Atlanta but some message boards tell me its JFK.
If anyone has travelled on this flight before can you please let me know.

Thanks.

[waitin_toolong]

I doubt that the people do baggage claim at JFK, infact I doubt if they even deplane there. so in that case they will do immigration at atlanta