Explanation/Reference:
You can use mobile device mailbox policies to manage many different settings. These include the following:
Require a password

Specify the minimum password length

Require a number or special character in the password

Designate how long a device can be inactive before requiring the user to re-enter a password

Wipe a device after a specific number of failed password attempts

References: https://technet.microsoft.com/en-us/library/bb123783(v=exchg.160).aspx