Employers aren't stupid (most of them, at any rate). They know that when employees are allowed to access work email on a personal smartphone, they will check email 20+ times per day more and end up working as much as two extra hours each day. The Telegraph notes that nearly 9 out of 10 office workers can access work email on their phones, and two-thirds of them check email as soon as they wake up, and right before they go to bed.