According to multiple archived threads within the Trump sanctuary, /pol/ on 4chan. It would seem the Apple account information of John Podesta was discovered and hijacked by an anonymous user.
From: eryn.sepp@gmail.com
To: john.podesta@gmail.com
Date: 2015-05-16 14:41
Subject: Re: Apple IDI do. Sorry been moving. Just in case Milia hasn’t gotten it to you let:
Apple ID: john.podesta@gmail.com
Runner4567
The user went on to vandalize the account by changing the profile image with foul imagery. The account has since been locked by Apple.
This information isn’t necessarily groundbreaking other than the fact that it may legitimize the E-mails being released by Wikileaks.
Link: Wikileaks E-mail