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How to Unblock a Mobile Device in Exchange Server

Heidi asks:

“I accidentally blocked a user and I need to allow them. How do I unblock them?”

When a mobile device is being blocked by Exchange ActiveSync, there are two ways that you can unblock it. The first is using the Exchange admin center for Exchange 2013/2016. Navigate to the mailboxes view, select the mailbox in question, and in the right-hand pane click the View details link under Mobile Devices. The list of mobile devices associated with at user will be displayed, and you can highlight the device you want to unblock and click the Allow button, then save the change.


This change will add the device to the user’s allowed devices list. If you’d prefer to just remove the device association, click the delete button instead.

The other method is to use the Exchange Management Shell. Run the Get-CASMailbox cmdlet to see the blocked device IDs for the user.

To add a blocked device ID to the allowed device ID list, use the Set-CASMailbox cmdlet.

Alternatively, you can just remove it from the blocked device ID list.

Or, if you’d prefer to just remove the device association, use Remove-MobileDevice.

Paul is a Microsoft MVP for Office Servers and Services. He works as a consultant, writer, and trainer specializing in Office 365 and Exchange Server. Paul is a co-author of Office 365 for IT Pros and several other books, and is also a Pluralsight author.
Category: Exchange Server


  1. Aravind says:

    Hello Paul,

    Thanks for your great article.

    Is there a way to block CloudMagic App connections in Exchange Active sync.

    Even tried in adding in Device Access rule but that doesn’t work and also tried in blocking in using the following command and that too doesn’t work.

    Set-casmailbox -identity “abc@abc.com” -EwsBlockList EWS/*, OWA/*

    Since CloudMagic app is using EWS method and Active sync polices are not getting applied.

    Could you help me out.


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