This is my first post on the Cloudflare community. Our DMARC provider (OnDMARC) has made a recommendation for me to configure FCrDNS to further improve the security and deliverability of email. I’m not sure what steps are required to complete this with Cloudflare and Office365. Has anyone done this before? Here’s a bit more info about FCrDNS for context.
Forward-confirmed reverse DNS (FCrDNS) is a spam filtering mechanism that tests if a given IP address has both forward (name-to-address) and reverse (address-to-name) Domain Name System (DNS) entries that match each other.
This verification is a weak form of authentication that exists to prove that there is a valid relationship between the owner of a domain name and the owner of the network that has been given an IP address. As this is difficult for spammers and spoofers to bypass FCrDNS is checked by some mail receivers in an effort to reduce phishing attacks and spam.
Legitimate email servers should be correctly configured for FCrDNS to avoid deliverability issues.