Convert resource mailbox to cloud only

Copper Contributor

Hi

 

During migration to 365 we migrated our resource mailboxes (room/equipment) by using AAD Connect and New-MailboxMove command. Now we would like to clean up in on premise AD and convert these mailboxes to be cloud only, it is also a requirement since we want to use MTRs in the rooms.

Is there any support way to convert them to cloud only and remove the link to on prem?

 

Thanks

Peter

6 Replies

Hi @PSonander,

here's a detailed step-by-step guide on how to convert on-premises resource mailboxes to be cloud-only in an Exchange Online (hybrid) environment:

Note: This process assumes that you have already migrated the resource mailboxes to Exchange

Online as part of your hybrid deployment.

  1. Backup Data: Before making any changes, ensure you have a reliable backup of the data associated with the resource mailboxes. This includes emails, calendar items, and other mailbox content.

  2. Verify Mailbox Locations:

    • Confirm that the resource mailboxes are currently synchronized and available in your on-premises Active Directory.
    • Ensure that they are accessible in Exchange Online and are functioning as cloud-only mailboxes.
    • You may need to disconnect the mailbox from the on-premises user account. To do this, use the Disable-Mailbox cmdlet in your on-premises Exchange environment. This cmdlet removes the mailbox from the on-premises Active Directory user account without deleting it. For example:

 

Disable-Mailbox -Identity "OnPremUser"

 

  • Recreate Mailbox as a Cloud-Only Mailbox:

    • After disconnecting the mailbox from the on-premises user, you can create a new cloud-only mailbox for the resource. This is typically done in Exchange Online PowerShell. Here's an example of how to create a new mailbox:
     
     

 

New-Mailbox -Alias "CloudResourceMailbox" -UserPrincipalName "email address removed for privacy reasons" -PrimarySmtpAddress "email address removed for privacy reasons" -DisplayName "Cloud Resource Mailbox"

 

 

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Kindest regards,


Leon Pavesic (LinkedIn)

@LeonPavesic will this recreate the old mailbox with all current bookings or will there be a completely new empty mailbox?

 

Thanks

Peter

Hi @PSonander,

thanks for the update.

no, recreating the mailbox as a cloud-only mailbox will create a completely new and empty mailbox. This means that any existing data, such as previous bookings and emails, will not be automatically transferred to the new mailbox. You will need to manually migrate or re-enter the existing data and bookings into the new cloud-only mailbox.

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Kindest regards,


Leon Pavesic
(LinkedIn)

I see, my question was how to convert a resource mailbox to be cloud only, not how to create a new resource mailbox. I need a solution to convert it without loosing all data in the mailbox

@PSonanderDid you find a solution to this?  We want to move all of our resource and shared mailboxes to M365 only (that is, no longer dependent on an on-prem AD account existing).  Finding accurate information on how to do that is proving challenging.

@shawnsarnia no I have not found any supported way of doing it. 

 

What I have done in some cases is to remove the onprem AD account from the scope of the EntraID Connect, effectively deleting the account in EntraID. Then doing a restore from EntraID side. This has worked but is as far as I know not supported by Microsoft