Details
You can configure this setting to require strong passwords to unlock mobile devices before they can connect via ActiveSync to an Exchange server.
Rationale:
Allowing simple passwords can make it easier for an attacker to correctly guess them.
Solution
To implement the recommended state, execute the following PowerShell cmdlet:
Set-MobileDeviceMailboxPolicy -AllowSimplePassword $false
Supportive Information
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: Identification and Authentication.This control applies to the following type of system Windows.