Reverse DNS Lookup (rDNS / PTR)
Inspect IPv4 and IPv6 pointer (PTR) records, test Forward-Confirmed Reverse DNS (FCrDNS), and ensure your outbound mail server IP is verified.
Why is Reverse DNS critical for email deliverability?
While normal DNS maps a hostname to an IP address, Reverse DNS (rDNS) performs the opposite: looking up an IP address in the special 'in-addr.arpa' zone to find its domain name.
Strict Spam Filter Requirement
Major email providers (including Google Workspace, Outlook, and Yahoo) will reject or heavily penalize incoming SMTP connections from IP addresses with missing or generic reverse DNS.
FCrDNS Alignment
Forward-Confirmed Reverse DNS means the IP resolves to a hostname (via PTR), and that same hostname resolves back to the original IP (via A). This confirms server identity.
Configured with Your ISP
Unlike normal DNS records managed on Cloudflare or Route53, PTR records must be configured with the hosting provider or cloud network that allocated your IP block (e.g. AWS, DigitalOcean).
Automate your email deliverability
Mailofly provides automated DKIM rotation, dedicated IP pools, and zero-downtime multi-provider failover. Send your first 10,000 emails free.