For some reason, the act of approving a quarantined device using EMS isn't immediately obvious. It took me a little while to work out how to do it.
This command will show you what devices are quaranted:
Get-ActiveSyncDevice -filter {deviceaccessstate -eq 'quarantined'} | select identity, deviceid | fl
Therefore it would seem that set-activesyncdevice would be the correct command to use to approve the device.
Not so.
It is actually set-casmailbox.
Take the device ID from the first command, you use it to complete this second command:
Set-CASMailbox –Identity user@example.com –ActiveSyncAllowedDeviceIDs DEVICEID
Give it about 15 minutes and the device will start to get email.
