https://docs.cloud.google.com/python/docs/reference/appengine/latest/google.cloud.appengine_admin_v1.services.authorized_domains
Package authorized_domains (1.17.0) | Python client libraries | Google Cloud Documentation
authorized domains
https://forminit.com/docs/authorized-domains/
Authorized Domains | Forminit
Restrict form submissions to specific domains. Unauthorized submissions are automatically flagged as spam by Forminit.
authorized domainsforminit