The Gmail Signatures app requires special access to your corporate Gmail in order to upload signatures to all users in your Google Workspace. With this permission, the app will also automatically upload your users' personal data into signatures, update personal data if it changes, and create signatures for new employees.

Workspace permissions: Super admin

Note: It can take several minutes for your change to take effect

Step by step

1. Log in to the Google Workspace console with your Super Admin account

2. Click on the Security tab in the side menu, then click on API controls

3. Scroll to the bottom of the page

4. Click the Manage domain wide delegation button

5. Click Add New button

6. In the pop-up window, fill in the following data 

- Client ID: 109086505979807752527

- OAuth Scopes:,

7. Click Authorize button