Certificate-centered connector configuration: Be sure that your on-premises email server is configured to make use of a certificate to deliver email to Microsoft 365, plus the Popular-Name (CN) or Subject Alternate Name (SAN) in the certificate incorporates a domain title you have registered in Microsoft 365, and you have designed https://socialbuzzmaster.com/story2619733/the-smart-trick-of-postal-smtp-setup-that-nobody-is-discussing