The Global Address List (GAL) in an Exchange Server is the go to place to find a comprehensive list for all the objects in Exchange Sever which are mail-enabled. The address list contains the contact information of the following items:
- Users
- Distribution Groups
- Shared resources, such as shared mailboxes, conference rooms, and equipment.
As the GAL is a vital component, you also need to migrate this list to Office 365 (Microsoft) when migrating from on-premises Exchange to Office 365. Below, we will discuss the ways to migrate GAL to Office 365.
Methods to Migrate GAL to Office 365
You can migrate the Global Address List (GAL) information to Office 365 by following the below-mentioned methods.
Method 1: Using Hybrid Deployment
In hybrid deployment, the local Exchange Server and the Exchange Online act as one system. The hybrid model assists in migrating data and resources in a smooth way and with minimal impact on the users.
The hybrid method requires some preparation to setup. This involves updating all the local Exchange Servers to the latest Cumulative Updates (CU) and Security Updates (SU), and opening the necessary ports with no restrictions or limits. In addition, you must have the Mailbox Replication Service (MRS) proxy running on the Exchange Web Services (EWS) virtual directory.
The next step is to download the Hybrid Configuration Wizard (HCW) and install it. Once done, you need to enter the local Exchange Server information with a user who has administrative permissions on the server as well as the Office 365 Global Administrator. Then, you have to set up the Federation Trust using the wizard, along with the connectors and the OAuth for authentication between Exchange Server and Exchange Online. Once this is done and all is working, the Global Address List (GAL) will be synchronized with Exchange Online (Office 365).
Some common challenges that you might encounter are:
- Closed ports on the network or network misconfiguration.
- The process works heavily with certificates since it uses federation trusts. An expired certificate will impact the migration of data.
- The migration process will take a significant amount of time and resources.
Method 2: Using Microsoft Entra Connect
Microsoft Entra Connect, formerly known as the Azure AD Connect, can be used to synchronize the Global Address List (GAL) from the local Exchange Server to the Exchange Online. It is a one-way synchronization for the resources. This means that changes to the distribution groups, shared mailboxes, and other resources can only be done from the local Exchange Server or Active Directory server.
For this, you need to download the Microsoft Entra Connect from the Microsoft website. Before downloading, make sure that the all the requisites are met. It is recommended to install the Microsoft Entra Connect on a member server and not on an Active Directory Server. After installation, run the installer and follow the onscreen instructions.
The next step is to configure the synchronization on the application. Open Entra Connect and configure the on-premises Active Directory account with all the necessary permissions on the Active Directory Schema. Then, set the destination, which is Exchange Online. You should enter the global admin of the Office 365.
The next step is to select the synchronization attributes, such as display name, mail, or even security group membership. These are needed to identify the objects to synchronize with Microsoft Entra Connect.
Once all is set, you should run the initial synchronization process, which will extract the information from the Active Directory, sanitize and prepare it for migration, and then create the object in Microsoft Entra with the same attributes. You should use the identity console to manage and monitor the synchronization.
After the synchronization is complete, the objects should be visible in Office 365 and marked as Directory Synchronized.
Method 3: Using an EDB Converter Tool
You can also look for alternative tools which will facilitate the entire data migration of Exchange Server, including the Global Address List (GAL). One such tool is Stellar Converter for EDB that can assist with the Global Address List (GAL) migration as well as with all the aspects that you can think of when it comes to migrating data and resources from local Exchange Server to Office 365.
Stellar Converter for EDB can seamlessly open live Exchange Server databases or offline databases from any Exchange Server version and of any size, with no need for an Exchange Server. The tool shows the entire structure of the database and offers a full HTML preview. It can granularly export the EDB data directly to Microsoft 365. The tool can process user mailboxes, user archives, shared mailboxes, public folders, disabled mailboxes, and even purged/deleted items with ease and assurance.
Apart from the challenges of configuration and implementation that you can go through and also considering the risks involved, you should consider the implications that might be involved if the operation would fail, impacting uptime of the server and the business.
Takeaways and Conclusion
Above, we have mentioned three different methods to migrate Global Address List (GAL) from local Exchange Server to Office 365. Let's compare these methods and try to find the best option that can streamline the process.
A hybrid setup can be the ideal as you can migrate the Global Address List with minimal impact to the business, if all goes well and no issues are encountered. However, you would need to consider the cleanup, the administrative effort to set it up and maintain it, and the implications on the server if there is any misconfiguration. You should also consider the expertise and skills needed to perform the migration.
With the Entra Connect, which is the easiest method, you can synchronize only the objects. Any data that comes with it will not be migrated. You have to also consider that a mistake can create multiple and unwanted objects in Microsoft Entra and to clean it up might consume a lot of time and resources.
With specialized tools, like Stellar Converter for EDB, you can reduce the challenges that you might face and also streamline the migration process. In addition, if anything happens, there will be no problem as you can continue with the project or move.