Source: https://docs.microsoft.com/en-us/briefing/be-admin
Office 365 Admin Center > Setting > Org Setting > Briefing email > uncheck “Let people in your organization receive Briefing email”
Source: https://docs.microsoft.com/en-us/briefing/be-admin
Office 365 Admin Center > Setting > Org Setting > Briefing email > uncheck “Let people in your organization receive Briefing email”