Graymail refers to solicited marketing emails and comes from a legitimate source. Your users once subscribed to them and now may no longer open or read them. As a result, graymail falls into a category between spam and desired emails.

As a customer admin, you can enable this feature to treat all graymail as malicious. Once enabled, an alert banner is added to graymail for all your users. Graymail is always auto remediated.