To help combat phishing attempts and for users to be able to visually identify their legitimate emails against phishing attempts, Google has implemented the Gmail "Authentication icon for verified senders" lab. If you enable this lab, you will see a key icon next to authenticated messages from trusted senders. Trusted senders match the following criteria:
- Send a high volume of messages over time that most Gmail users think are not spam.
- Public a DMARC reject policy, which means that the domain only sends authenticated mail and any unauthenticated mail sent by the domain should be rejected.
For additional information on Gmail's Authentication Icon, please visit the Google Support page: https://support.google.com/mail/answer/3070163?hl=en
For information on how to configure DMARC, please review our knowledge base article: https://agari.zendesk.com/entries/25141091-How-do-I-configure-my-DMARC-record-