Home > Support Articles > Global Address List (GAL) Sync > Sync GAL for two Tenants without GAL Sync

Acme construction company has their email hosted in an Office 365 tenant with 550 mailboxes. They have been syncing the GAL to about 500 staff members with iPhones using our SaaS solution.

A few months later, they acquire Roadrunner Construction Company which also has their email hosted on Office 365 with 160 mailboxes.

Most of my staff can exactly guess the next question we will get from the Acme IT Manager:

“Will your software sync the GAL of two different Office 365 tenants?”

We often get the request to sync be able to sync the GAL of two tenants and we have it working now — but we cheated. We have a perfect GAL Sync solution without actually syncing the two GAL’s.

How does it work?

Acme construction created a new mailbox called “Acme Staff Export” and added it to the GAL target collection. On the next sync task, it also received an ACME GAL contacts folder just like every smartphone user.

This mailbox had nothing else in it. They gave it an email address of [email protected] with a strong 16 character password. Note that this is a user mailbox with no particular permissions. (It isn’t an administrator). These credentials can only access this one mailbox.

In the Road Runner tenant, the email administrator setup the CiraSync dashboard and proceeded to create a new contact list:

They saw this wizard with the different contact source types:

After selecting the option called “Shared Mailbox of another Company”, they are immediately prompted to provide the email address of the Staff Export mailbox at Acme:

Office 365 Shared Mailbox Remote Tenant

When they click the sign in button, they are presented with a familiar logon prompt from Microsoft:

After they authenticated and granted consent, a new connector was available to navigate to the folders in the ACME staff export mailbox:

After choosing ACME GAL, as the source, now it’s time to pick the targets (who gets the ACME GAL) so they clicked All Mailboxes shown at step (A)

After their selection, All Mailboxes appeared as shown in step (B). This sets up the sync so that everyone in the Road Runner Construction tenant will get a copy of the ACME GAL. Not everyone had to be targeted. Later on they may build a collection and filter the sync targets.

After they click Next shown at (C), they see the last and final step of the wizard. It is quite important to set the contact list name (D) as each target contact will have a category set to that name.

Since all of the users at RoadRunner have iPhones, they can safely put contacts in an ACME GAL subfolder (E).

After saving the changes in the final step of the wizard, they use the CiraSync dashboard to run a sync task for the entire Roadrunner tenant. In about one hour, all of the users in Roadrunner Construction have the ACME GAL available on both Outlook, and they iPhones.

They have now completed one half of the GAL to GAL sync. They should first start by pushing the Roadrunner GAL to all Roadrunner smartphone users. Next they would create a [email protected] and it set as a target of the GAL Sync. Finally, they would set up a contact list on the ACME tenant to read and the Roadrunner GAL to all ACME users.


Please Note: The companies named here are made up and do not reflect any actual companies.