Office 365 mailbox has guid different than on-prem mailbox

Sai Manasa Chintakunta 1 Reputation point
2021-03-18T19:43:14.99+00:00

Hi,

We have a issue where we enabled remote mailbox for user and it doesn't populate in Office 365. We have this message "We are preparing mailbox for this user" message in office 365.

We again disabled the remote mailbox, wait for 2 syncs, enable the mailbox, wait for the sync, set archive guid and then i left it for entire day and magically the mailbox appeared in Office 365.

But a new problem started as the guid of Office 365 mailbox is different than On-prem mailbox. I tried various ways to connect both of them and was not successfully.

Any suggestion would be appreciated.

Thank you.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Lucas Liu-MSFT 6,161 Reputation points
    2021-03-19T06:12:01.427+00:00

    Hi @Sai Manasa Chintakunta ,
    Is your environment a Exchangne hybrid deployment environment?

    According to your description, do you mean that the same AD account has both an on-premises Exchange mailbox and an O365 mailbox? If so, based on my knowledge this is not feasible. It will create mail flow issues. Please following the steps in the below link to recover. In order to protect the mailbox data, please backup the mailbox before operation.

    Please refer to: How to recover when a mailbox exists in both Exchange Online and on-premises and My user has a mailbox both on-premises and in Exchange Online. Help!

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