Email allowlist - A list of IP addresses you define as approved to send mail to your domain. If you notice that legitimate emails from specific contacts are incorrectly marked as spam, you can allowlist the contact's IP address. After you allowlist an IP address, messages originating from the IP address are no longer marked as spam. Add IP addresses to allowlists in Gmail.
Email denylist - A list of email addresses you block from sending mail to your domain. Administrators can block domains or specific users using the Blocked senders setting. In addition, users can create a filter in their mailboxes to automatically send messages from specific users or email list to the Trash. Users can also prompt our spam filters by reporting unwanted messages as spam.