Set up Calendar Interop

(Optional) Allow Calendar users to book Exchange resources

You can let your Calendar users book Microsoft® Exchange calendar resources, such as meeting rooms, when they schedule a meeting. 

Set up Exchange resource bookings

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Step 1: Create role accounts on Exchange

First, you need to set up 10 mailbox role accounts. These accounts are in addition to the role account you created in Allow Calendar users to see Exchange availability data. Google uses these role accounts to check the availability of Exchange calendar resources. You need 10 accounts for load-balancing purposes. 

Set up the role accounts

  1. Verify that the role account you created in Allow Calendar users to see Exchange availability data is a mailbox account and not a mail user account. 
  2. Set up 10 additional mailbox role accounts on Exchange. You should reuse the password from the role account you created in Allow Calendar users to see Exchange availability data.

    For details on creating mailbox accounts, see the following Microsoft instructions:

Example: Create the role accounts in Exchange PowerShell

$password = (ConvertTo-SecureString -String 'password' -AsPlainText -Force)
for ($i=1; $i -le 10; $i++) { New-Mailbox -name "Calendar Interop Load Balancing Account $i" -userprincipalname "calendar_interop_load_balancing_account$i@your_domain" -password
$password }

Example: For Office 365®

$password = (ConvertTo-SecureString -String 'password' -AsPlainText -Force)
for ($i=1; $i -le 10; $i++) { New-Mailbox -name "Calendar Interop Load Balancing Account $i" -MicrosoftOnlineServicesID "calendar_interop_load_balancing_account$i@your_domain" -password
$password }

Make sure to replace the password and your_domain fields with the appropriate values.

Step 2: Make Exchange calendar resources available

To make Exchange calendar resources available to Google Calendar users:

  1. In Exchange PowerShell, run the Set-CalendarProcessing command.
  2. Repeat the command for each Exchange resource that you want available. 

    Example: Set-CalendarProcessing -Identity "Room 221" -ProcessExternalMeetingMessages $true

    For details on the Set-CalendarProcessing command, see the Microsoft documentation.

Step 3: Create a filter for G Suite users

Create a filter that allows booking requests only from your G Suite users. To do this, in Exchange set up a mail flow rule using the following parameters:

  • Apply this rule if and then The recipient is, then enter all the resources you want to be able to be booked from Calendar (for example, 
  • Do the following and then Block the message, then select Delete the message without notifying anyone
  • Except if and then The sender's domain is, then enter your G Suite domain.

Important: Add your Exchange domains to the list of exceptions to the blocking rule to make sure you don't block email coming from your Exchange users.

For details on creating mail flow rules, see the Microsoft documentation.

Step 4: Create a room list distribution group

Create a room list distribution group for Exchange resources.The distribution group contains the list of Exchange calendar resources that are available to G Suite users. For details on setting up a room list distribution group, see the Microsoft documentation.


  • You can have only one distribution group in your Calendar Interop setup. 
  • You must name the distribution group Calendar Interop Resources.
  • An Exchange resource that you add to the group cannot have the same name as a resource in Google Calendar.

Example: Add all rooms to the group

$Members = Get-Mailbox -Filter {(RecipientTypeDetails -eq "RoomMailbox")} | Select -ExpandProperty Alias

New-DistributionGroup -Name "Calendar Interop Resources" -RoomList -Members $Members

To make sure the correct rooms are added to the newly created group, run this command:

Get-DistributionGroupMember "Calendar Interop Resources"

Step 5: Refresh the Exchange resources
  1. Open Calendar Interop Tools.
  2. Next to Resource list test, click Refresh

    You should see the resources that you added in step 2. It can take up to 30 minutes for the resources to appear.

  3. Go back to Calendar Interop Tools.

  4. Next to Resource availability lookup tester, enter the email address of an Exchange calendar resource.

  5. Click Perform test.

    You should see the test executed successfully 10 times: one test for each load-balancing account.

Step 6: Turn on Exchange resource booking for your domain

Important: Make sure you sign in to your primary domain.

  1. Sign in to your Google Admin console.

    Sign in using your administrator account (does not end in

  2. From the Admin console Home page, go to Appsand thenG Suiteand thenCalendar.
  3. Click Calendar Interop management.
  4. Under Interoperability features, check the Enable Exchange room booking box.
  5. Click Save Changes.
Step 7: Verify the Exchange resource booking setup
  1. Sign in to a G Suite account.
  2. In Google Calendar, create an event.
  3. On the right, click Rooms.

    The Exchange resources you added appear as a suggested room.

  4. Click the rooms or resources you want to add to the event and then Save.

    For more information, see Add a room to an event.

  5. If prompted, select Invite external guests.

    A booking email is sent to the Exchange resource and the resource is booked.

  6. If the resource isn't booked, make sure the resource is available. For details, see step 2 (above) for details. 
If you use Google Cloud Directory Sync (GCDS)

If you're syncing Exchange resources to G Suite with GCDS, you need to ensure G Suite users don't see the same resource twice (once from each system) in order to avoid duplicates.

Example: Using Exchange resources through Calendar Interop

You can have users access the Exchange resources through Calendar Interop instead of the G Suite resources. In this case, we suggest that you delete the resources from G Suite and set up Calendar Interop room booking as usual. 

Important: The contents of resource calendars on Google will be lost.

Learn more about calendar resource syncing.

Example: Using a mix of G Suite and Exchange resources

You can use some resources from both G Suite and Exchange. In this case, and to avoid resources showing as duplicates, make sure that:

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