Some Exchange-related attributes on target object are not modified when "Only Update Mailboxes'' exchange option setting is enabled. Checking this box will cause Directory Sync Pro for Active Directory to only update those objects that are mail-enabled.
When a DirSync profile is configured with the "Only Update Mailboxes" exchange option checked, the Exchange-related attributes on the target object are not modified when a change is made to the source object.
This is a by design limitation. The following attributes are not changed on the target object when a change is made on the source object:
-Target Address
-Proxy Address
-msExchPoliciesIncluded
-msExchPoliciesExluded
-showInAddressBook
-pwdLastSet
-mail
