To got these result I used following powershell command:
Get-ActiveSyncDevice | select-object UserDisplayName,DeviceModel,DeviceOS,DeviceType,DeviceMobileOperator,FirstSyncTime,DeviceAccessState,DeviceImei,LastSuccessSync,IsValid | sort-object UserDisplayName | Ft -autosize -wrap | Out-File c:\mobiledevices_1_00.txt -width 600
If you like you can add more fields.
After that I found that LastSyncDate field was empty.
To override this problem I found following command that create a relationship between DeviceID (that you can find in first query too) and LastSucceSync field
Get-ActiveSyncDevice | Get-ActiveSyncDeviceStatistics | select-object DeviceID,LastSuccessSync,Identity |export-csv c:\mobiledevices_1_00_last_sync.csv
For security reason you can proceed to disable any user that has enable OWA/ActiveSync feature, but for user that we want enable only company devices you can use this woraround.
To block any further device you can put all new devices (by default) in Quarantine.
About that you can follow this article:
Only IT could accept ActiveSync activation users requests.
Another key point is that, Exchange 2010, give you the ability to remotely wipe any devices ActiveSync connected in case if you lost it or someone stole it.
http://technet.microsoft.com/it-it/library/aa998614%28v=exchg.150%29.aspx
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