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If you see Disable Exchange ActiveSync, this means that ActiveSync is enabled for the user.Under Mobile Devices, take the following actions: In the list of mailboxes, double-click the user, and then select mailbox features.
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In the left navigation pane, select recipients, and then select mailboxes. Select Admin, and then select Exchange to open the Exchange admin center. Sign in to the Microsoft 365 portal as an admin. Resolution - Step 1: Confirm that ActiveSync is enabled for the user
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These include, but aren't limited to, the following: However, the mobile device previously could connect. A user's mobile device can't connect to Microsoft Exchange Online in Microsoft 365 through Microsoft Exchange ActiveSync.
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