"Class: SECRET— Reason: 1.4(B), 1.4(D) — Declassify on: 05/27/2036," reads the header of Kerry’s email to Clinton dated May 19, 2011, and released by the State Department on January 29.
The closing part of the email reads "Sent from my iPad."
On Tuesday, State Department spokesman John Kirby said Kerry’s email was sent "from a non-official account," which he said was "no longer active."
Kirby said 18 emails exchanged between President Barack Obama and Clinton had been withheld from FOIA to protect his ability to receive "unvarnished advice and counsel." White House spokesman Josh Earnest estimated the emails would be released five years after Obama leaves office.
Clinton, who won the first official nomination race in the Iowa caucuses by a razor-thin 0.2 percent margin on Tuesday, has been mired in a scandal for using a private server and a personal email account for official purposes during her tenure as State Secretary.
Kerry chaired the Senate Foreign Relations Committee before succeeding Clinton in 2013.
