Purpose
This test determines if there is a valid forward-confirmed reverse Domain Name System (FCrDNS) verification for your IP address and host name. Mailbox providers consider FCrDNS as part of a correctly configured infrastructure.

How it works
When a campaign message is sent to Inbox Monitor, Inbox Optimizer performs a FCrDNS check on each sending IP address and host name associated with the campaign.

The Domain Name System (DNS) checks performed at the time the campaign was sent to Inbox Monitor may not reflect a recent change. DNS changes may take up to 48 hours to be reflected correctly across the internet, so Inbox Optimizer may need 48 hours to display the correct result.

Results

• Pass: If the reverse Domain Name System (rDNS) lookup on the IP address points to a valid host name and the DNS lookup on the host name points back to the sending IP address.
• Fail: If the reverse Domain Name System (rDNS) lookup on the IP address does not point to a valid host name or the DNS lookup on the host name does not point back to the sending IP address.