How to block ActiveSync for Office 365 users in Exchange Online

Navigate to the Exchange Control Panel

Browse to the Exchange Control Panel: http://outlook.office.com/ecp

Select mailboxes and search for the mailbox you want.

Select the mailbox you want from search.

For mailbox features, select -> Disable Exchange ActiveSync

Under mailbox features -> under phone and Voice Features -> choose Disable ActiveSync.

Requesting mobile devices via AciveSync?

Via the option View details (as shown in the image above) you can view all currently connected devices.

Log in via PowerShell in Exchange Online

These instructions will connect you to Exchange Online with PowerShell.

Block ActiveSync via Microsoft PowerShell

Set-CASMailbox -Identity <Mailbox ID> -ActiveSyncEnabled $False

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