Here are the steps:

1. In the Admin console Go to Apps > G Suite Gmail > Advanced settings.


2. Scroll to the Spam section, hover over the setting, and click Configure.


3. Enter a unique name for the setting


4. Check the Bypass spam filters for messages received from addresses or domains within these approved senders lists box.


5. Click Use existing or create a new one, enter a new list name, and click Create.


6. Hover over the list name, click Edit, and then click Add.


7. Enter domain name ‘abc.com’ or add email address.


8. Save







https://www.comprompt.co.in/how-to-whitelist-domain-in-gsuite/