How to Check and Configure Reverse DNS (PTR Records)
Reverse DNS maps an IP address back to a hostname, the opposite of a standard forward DNS lookup. For mail servers, a properly configured PTR record is essential. Receiving servers use reverse DNS to verify that the sending IP belongs to a legitimate mail server, and missing or mismatched rDNS is one of the top reasons emails land in spam or get rejected outright.
Check your reverse DNS now
Use our free Reverse DNS Lookup tool to see the PTR record for any IP address and verify it matches your mail server hostname.
Step 1: Find Your Mail Server's IP Address
Before checking rDNS, you need to know which IP address your mail server uses for outbound email. Look up your domain's MX records with the MX Lookup tool, then resolve the MX hostname to an IP address. If you run your own server, check your server's network configuration.
Step 2: Query the PTR Record
Enter the IP address in the Reverse DNS Lookup tool. You can also query from the command line:
dig -x 203.0.113.10 +short
# or
nslookup 203.0.113.10The result should return a fully qualified domain name (FQDN). If you get NXDOMAIN or no result, there is no PTR record for that IP.
Step 3: Verify Forward-Confirmed Reverse DNS
The gold standard is Forward-Confirmed Reverse DNS (FCrDNS). This means the PTR record for your IP returns a hostname, and that hostname's A record resolves back to the same IP. Both directions must match:
# Reverse: IP → hostname
dig -x 203.0.113.10 +short
# Result: mail.example.com.
# Forward: hostname → IP
dig mail.example.com A +short
# Result: 203.0.113.10Step 4: Request or Update the PTR Record
PTR records are controlled by the IP address owner, not your domain registrar. Contact your hosting provider or ISP and request that a PTR record be set for your server's IP. Provide the hostname you want it to resolve to (e.g., mail.example.com). Most cloud providers like AWS, Google Cloud, and DigitalOcean let you set PTR records through their dashboard.
Step 5: Align rDNS with SMTP Banner
For maximum deliverability, make sure your PTR hostname matches your SMTP HELO/EHLO banner. Use the SMTP Banner Test tool to check what your server announces. If there is a mismatch, update your mail server configuration to use the same hostname as your PTR record.
Frequently Asked Questions
Why does my mail server need reverse DNS?
Many receiving mail servers check that the sending IP has a valid PTR record that resolves back to the IP. Without it, your emails are more likely to be rejected or flagged as spam. Google, Microsoft, and Yahoo all recommend proper rDNS configuration.
Who manages PTR records?
PTR records are managed by whoever controls the IP address block, which is typically your hosting provider or ISP. You cannot set PTR records in your domain's DNS zone. Contact your hosting provider to request a PTR record for your server's IP.
Should the PTR record match my SMTP banner?
Yes. Best practice is to ensure your PTR record, SMTP HELO/EHLO hostname, and forward DNS all match. This is called Forward-Confirmed Reverse DNS (FCrDNS) and significantly improves mail server trustworthiness.