Microsoft added a feature called “Allow/Block/Quarantine list” in the Exchange 2010. This feature was designed to help IT organizations control which of the growing number of Exchange ActiveSync-enabled devices are allowed to connect to their Exchange Servers. With this feature, organizations can choose which devices (or families of devices) can connect using Exchange ActiveSync (and conversely, which are blocked or quarantined).
“Note; that ABQ list isn’t meant to displace policy controls implemented using Exchange ActiveSync policies. Policy controls allow you to control and manage device features (such as remote wipe, PIN passwords, encryption, camera blocking, etc.) whereas ABQ list is about controlling which devices are allowed to connect (for e.g., there may be a lot of devices that support EAS PIN policies, but some IT departments only want to allow certain devices to connect to limit support or testing costs). The easy takeaway is that Exchange ActiveSync policies allow you to limit device access by capabilities while ABQ list allows you to control device access by device type.”