In the templates available to everyone in Rule, it says 'Certified by Rule'.

When billions of emails are sent around the world every day, it is important to be able to distinguish between senders who are serious and those who are less serious.

When Rule adds 'Certified by Rule' or 'Sent from Rule' in the footer of the template, the recipient of the email can click on the link and be directed to Rule.se. A recipient who is unsure if the email is from a reputable sender can then be reassured and choose to unsubscribe from future emails, instead of impulsively clicking the spam button.

Rule as the sender in the footer is therefore a quality stamp.