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A true two-way contact sync between Microsoft 365 GALs

GAL (Global Address List) is a list of contacts that are accessible to all users across Microsoft 365 (formerly known as Office 365) tenant. This list combines tenant user details, as well as organizational contacts and groups. In this article we will explore how you can use SyncPenguin to set up a complete two-way sync of GAL contacts between two or more Microsoft 365 tenants.

Sync setup completion time: 7 minutes.

Setting up the sync

Before you start, be sure to create a SyncPenguin dashboard account here. We provide a completely free 14-day trial, so you have a chance to test the syncing and ensure it works as expected.

Once signed in to the dashboard, head to the Synchronizations section and click + New sync button. After that, select Office 365 GAL Contacts connector as both ends of the sync as shown below. Be sure to not select regular Office 365 Contacts connector that is used to sync personal contacts of users.

GAL sync creation process

Then select the Two-way direction and click Create sync.

Connecting both GALs

Once created, you’ll see the main sync page. One of the sections of the sync page is Sync profile, which is the place where you need to connect both tenants.

Sync profile

To connect one of the tenants, click the Connect account button and follow the authorization steps. Note that you might need to provide the admin consent to be able to connect a non-admin user. Also note that SyncPenguin uses PowerShell to modify GAL contacts, so we require the Exchange management access scope. If you have any questions or issues with the connection, feel free to contact us.

The other tenant can be connected in a similar way.

Starting the sync

Once both tenants are connected, you are good to start syncing. This can be done in the Actions section of the dashboard. Click Start syncing and you’ll be prompted with the following window:

Start syncing

The start options you see instruct SyncPenguin on what to do initially with existing GAL contacts. In most cases you’d either two-way merge contacts between tenants, or merge from one tenant to another. You need to choose the option that better suits your situation and use case.

Once you make your choice, you need to click Merge and start continuous sync to active the syncing. Once the initial merge is completed, SyncPenguin will automatically execute the sync every 10 minutes (by default) to sync any new changes that occur to your GAL contacts.


You can also apply filters or field mapping adjustments in the Field mapping & rules section, where we provide a no-code interface to customize your sync. If you have any questions regarding customizations, feel free to contact us.


That is it! This is how simple it is to set up a two-way GAL sync using SyncPenguin. If you have any feedback or questions, feel free to contact us.

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