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Create Office 365 resource mailbox in Exchange hybrid

It’s good to through the Exchange hybrid test plan checklist before you start to migrate any mailboxes to Exchange Online – Office 365. One of the items is to create an Office 365 resource mailbox in Exchange hybrid configuration. In this article, we will look at the different options on how to create Office 365 resource mailbox in Exchange Hybrid.

Create Office 365 resource mailbox

There are two ways to create a resource mailbox in Exchange hybrid:

  • Exchange Admin Center
  • Exchange Management Shell
Good to know is that you don’t need to assign a license to a room mailbox or equipment mailbox.

Create Office 365 resource mailbox in Exchange Admin Center

Log into the Exchange Admin Center (EAC) with admin privileges. This is on the Exchange on-premises server and NOT Office 365. Click recipients in the feature pane and click mailboxes in the tabs. Click the + icon. Select Office 365 mailbox to create a new mailbox in Office 365.

Create Office 365 resource mailbox in Exchange admin center

Fill in the information. Ensure that you select a verified domain UPN suffix and not a local suffix such as .local or .lan. Select Room mailbox for Mailbox type. Click Save.

Create new Office 365 mailbox type room mailbox

Don’t forget to force sync Azure AD Connect or wait a maximum of 30 minutes before the sync is automatically run.

PS C:\> Start-ADSyncSyncCycle -PolicyType Delta

Click on the new room mailbox and click the edit icon in the toolbar.

Edit room mailbox Exchange admin center

Click email address in the menu. Verify that you see:

  1. smtp:@tenant.mail.onmicrosoft.com
  2. Remote routing address
Check email address smtp room mailbox

Go back to the Exchange admin center and click in the top bar on Office 365. Log in with your Microsoft 365 admin credentials. Go to recipients > resources. Click the Office 365 room mailbox and press the edit icon in the toolbar.

You will only see Office 365 mailboxes in Microsoft 365 Exchange admin center. The on-premises mailboxes are not shown on Microsoft’s cloud servers.

Edit room mailbox Office 365 Exchange admin center

In the menu, click on email address. There is no remote routing address option in the cloud, and you will see two smtp onmicrosoft.com email addresses:

  1. smtp:@tenant.mail.onmicrosoft.com
  2. smtp:@tenant.onmicrosoft.com
Check email address smtp room mailbox

In Active Directory Users and Computers, the AD-object shows up.

Room mailbox AD-object

We did create an Office 365 resource mailbox directly from on-premises Exchange admin center in Exchange Hybrid configuration. In this example, it was a room mailbox.

Create Office 365 resource mailbox with Exchange Management Shell

Run Exchange Management Shell as administrator. Make use of the New-RemoteMailbox cmdlet. Run the command to create a resource mailbox in Office 365.

[PS] C:\>New-RemoteMailbox -Room -Name "Test RoomMailbox2" -Firstname "Test" -LastName "RoomMailbox2" -UserPrincipalName "Test.RoomMailbox2@exoip.com" -OnPremisesOrganizationalUnit "OU=Resources,OU=Company,DC=exoip,DC=local"

Wait for Azure Active Directory synchronization or force sync Azure AD connect with PowerShell.

PS C:\> Start-ADSyncSyncCycle -PolicyType Delta

The room mailbox shows up in Exchange admin center.

Exchange admin center room mailbox

Click in the top bar on Office 365. Go to recipient > resources. Verify that you see the room mailbox.

Office 365 Exchange admin center room mailbox

Test room mailbox booking

We did create two Office 365 resource (room) mailboxes. Let’s test booking a room mailbox.

Log in to Amanda’s Outlook, which is an on-premises mailbox. Click on New items > Meeting.

Create new meeting in Outlook

Fill in the user you want to send the invite to and include the test room mailbox that you created in the earlier step. Click Send.

Fill in and send appointment

The meeting request is automatically accepted because that is the default behavior for new room mailboxes.

Request was accepted

Test GAL visibility in both organizations

It’s good to test the Global Address List (GAL) visibility in Exchange on-premises and Exchange Online (Office 365).

Exchange on-premises Global Address List visibility

From Amanda’s Outlook client, click on Address Book. Select the address book All Rooms. Verify that the Office 365 room mailboxes show up.

Office 365 mailbox test GAL visibility

Office 365 Global Address List visibility

From Test Mailbox1 Outlook client, click on Address Book. Select the address book All Rooms. Verify that you see the Office 365 room mailboxes.

On-premises mailbox test GAL visibility

The next time, we will look at how to create distribution group in Exchange hybrid configuration.

Conclusion

In this article, you learned how to create an Office 365 resource mailbox in Exchange hybrid configuration. There are a couple of options to create a room mailbox in Office 365. Choose the one that works best for you.

Did you enjoy this article? You may also like the course Exchange Hybrid. Don’t forget to follow us and share this article.

ALI TAJRAN

ALI TAJRAN

ALI TAJRAN is a passionate IT Architect, IT Consultant, and Microsoft Certified Trainer. He started Information Technology at a very young age, and his goal is to teach and inspire others. Read more »

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