Your organization recently deployed Google Workspace.

The Domain Shared Contacts API allows you to add external contacts to the Google Workspace directory, making them available to all users in the domain. This is the most effective and scalable solution for adding a large number of external contacts (like the 3,000 from Microsoft Exchange) to your Google Workspace environment. Once the contacts are added to the directory, they will be accessible to all users in Gmail and other Google Workspace apps.