Allow Quarantine Mobile Device

Please refer the below steps to  allow the quarantine state device activesync device  to allow state,

Before proceed the steps, note-down the mobile device ID  
 

Below command will display about the user device information, refer the device ID state is allowed or quarantine

Get-ActiveSyncDevice -Mailbox Aliasname | select user*,device* | fl

 
Below command will display only the allowed device IDs ,

Get-CASMailbox Aliasname | select ActiveSyncAllowedDeviceIDs 

Below command used to allow the device ID,

Set-CASMailbox Aliasname -ActiveSyncAllowedDeviceIDs "704294541"

 
Below command used to allow the more than one device,

Set-CASMailbox Aliasname -ActiveSyncAllowedDeviceIDs @{add="1560598775"}

 
Solution:2

We can try this solution in GUI mode also , refer the below steps

1. Login to https://webmail.domain.com/ecp
2. Click the  Phone & Voice , select the Activesync Access 
3.  Select the user name and click allow ( Make sure to sync the device below perform this steps)