The details about how to do this configuration are based on your on-premises email server. For Exchange Server, see the following articles: Cloudflare Managed DNS comes with designed-in DNSSEC to safeguard your end users from on-path attacks which will spoof or hijack your DNS data. Stick to the prompts https://letsbookmarkit.com/story17054449/the-smart-trick-of-business-email-that-nobody-is-discussing