Configure Exchange for classic Calendar Interop

From February 28, 2018, the classic Calendar Interop tool will not be available. You can use the new Calendar Interop tool instead. Learn about the new Calendar Interop tool.

To enable classic Calendar Interop, you need to make changes to your Microsoft® Exchange server configuration using your Exchange Management Shell. Follow these steps:

1. Create an Exchange public folder database
If you've already created an Exchange public folder database in the past, you can skip this step. The public folder database is not created by default in Exchange versions 2007 and higher.

To create the public folder database, please refer to Microsoft's How to create a new public folder database article.

2. Create an Exchange role account with a mailbox

You need to create or use an existing Exchange role account that has both an Exchange mailbox and public folder write access. Google will use this account to authenticate to your Exchange server and write Google calendar f/b data to your Exchange public folder database.

You can grant a local service account public folder write access within the Exchange Management Shell by using the following command:

Add-PublicFolderClientPermission -Identity <Public Folder Identity> -User <Domain\user> -AccessRights Owner

Here's an example of what that should look like:

Add-PublicFolderClientPermission -Identity "\NON_IPM_SUBTREE\SCHEDULE+ FREE BUSY\EX:/o=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)" -User ALTOSTRAT\gcal_svc -AccessRights Owner

You can read Microsoft's full list of instructions in its Add-PublicFolderClientPermission article.

Tip: If you are unsure of the identity of the public folder store, use the following command to get the complete identity details:

Get-PublicFolder -Identity "\NON_IPM_SUBTREE\SCHEDULE+ FREE BUSY" -GetChildren | fl

Note: The Exchange Information Store caches permission data. Please wait for a few hours for the permissions to take effect.

3. Configure the Exchange availability address space for your G Suite alias domain
Every G Suite domain is automatically given a test alias domain that you can use in this step. You can view your test alias domain by signing in to your Admin console and clicking More controls > Domains. You can also use any alias domain you may have added yourself in the past.

If your primary domain name in Exchange and G Suite are different, you can use your G Suite primary domain name in this step, as opposed to a domain alias. If, however, your primary domain names in Exchange and G Suite are the same, you'll need to use a G Suite domain alias.

Next, add your G Suite domain alias as an availability address space in Exchange and assign it the public folder f/b access method using the following command in the Exchange Management Shell:

Add-AvailabilityAddressSpace -ForestName <Google Alias Domain> -AccessMethod PublicFolder

Here's an example of what that should look like:

Add-AvailabilityAddressSpace -ForestName -AccessMethod PublicFolder

What is an availability address space? You can read Microsoft's Availability Address Space article for more information.

4. Create mail-enabled contacts in Exchange for your G Suite users

Create a mail-enabled contact (not a mail-enabled user)in Exchange for each G Suite user whose free/busy data you want to sync to Exchange. You must add a valid SMTP email address for each mail-enabled contact you create.

If you use the same primary domain name for both G Suite and Exchange, you'll need to add an email address within your G Suite domain alias to each of your mail-enabled contacts.

Why use an alias domain name?

Exchange determines its f/b access method based on the availability address space (which corresponds to the domain name) of the user it's querying. The interop service stores Google users' f/b data in your Exchange public folder database, but the default f/b access method for your primary domain in Exchange does not query the public folder. As a result, Exchange will not find a Google user's f/b data if the user's mail-enabled contact email address is within your Exchange primary domain (and, thus, your default availability address space). Creating a second availability address space using your G Suite domain alias and assigning it the public folder f/b access method solves this problem.

You can read Microsoft's help center articles for more information about creating mail-enabled contacts.

Once you've finished creating a mail-enabled contact for each Google user whose f/b data you'd like to sync, you'll need to make note of each contact's legacy distinguished name (LegacyExchangeDN) information, which you'll use in step #3 of the G Suite configuration.

Next steps: Configure G Suite for classic Calendar Interop

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