ceo's at this level have teams of executive assistants that cover all communications 24x7x365, for personal, work, and government liason. You don't think they actually read their own emails do you?
A former CEO of mine was known for keeping all his emails, forever. For this he needed special email storage arrangements from the IT team, including a laptop with a super-large HD.
If you ever turned up to a meeting and contradicted something you once said in an email, he'd be on to you in an instant.