Article ID: 2807149 - View products that this article applies to.
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In a hybrid deployment of on-premises Microsoft Exchange Server and Microsoft Exchange Online in Microsoft Office 365, you can configure free/busy information sharing so that on-premises users and cloud-based users can see each other's availability in Microsoft Outlook or Outlook Web App.
However, you can't grant permissions to create or edit items in another user's calendar cross-premises. That is, cloud-based users can't edit the calendars of on-premises users, and on-premises users can't edit the calendars of cloud-based users. For this level of access, especially when one user must act as a delegate for another user, both mailboxes must exist in your on-premises Exchange organization, or both mailboxes must exist in your Office 365 organization.
To move an on-premises mailbox to the cloud-based organization, or to move a cloud-based mailbox back to the on-premises organization, run the New Remote Move Request Wizard in the Exchange Management Console on the hybrid server. For more information about mailbox migration between the on-premises organization and the cloud-based organization, see the following wiki post in the Office 365 Community:
Exchange hybrid deployment – moving cloud-based mailboxes to the on-premises organization
Error messages that users may receive when they try to grant Write-level permissions or perform Write-level actions (such as deleting an appointment in another user's calendar in Outlook or Outlook Web App) include the following:
Still need help? Go to the Office 365 Community