Active-sync (aka Windows Mobile) is the wireless service built into Exchange for communicating with smart phones. Smart phones are any mobile devices with the Windows Mobile operating system, and other phones that license Active Sync from Microsoft, including Apple’s iPhone.
If while attempting to activate Active-sync you receive a warning message stating that the account limit for Active-sync users has been reached, then you must add the Active-sync resource to your account. See Add a Resource for details.
1.Log into the Control Panel.
The Control Panel’s main dashboard displays.
2. As illustrated above, select Mailboxes from the Exchange section of the main dashboard.
The Exchange dashboard displays:
3. As illustrated above, select the appropriate mailbox by clicking the Display name.
Mailbox Details for the selected mailbox display:
4: Click [Edit] at the bottom of the screen to make the Mailbox Details editable:
5: Place a check-mark beside Active-sync and click [Submit].
Active-sync is now activated, or enabled: