Free PTR Record Checker (Reverse DNS Lookup)
Verify your mail server's PTR record and ensure forward-confirmed reverse DNS (FCrDNS) for better email deliverability.
PTR Record Checker
Verify reverse DNS (PTR) records and forward-confirmed reverse DNS (FCrDNS) for your mail server
What is a PTR Record (Reverse DNS)?
Overview
A PTR (Pointer) record, also known as reverse DNS, maps an IP address back to a domain name. While regular DNS (forward DNS) translates domain names to IP addresses, reverse DNS does the opposite. PTR records are critical for email deliverability because many mail servers verify that the sending IP has a valid PTR record that matches the mail server's hostname.
How PTR Records Work
- Email Sent: Your mail server sends an email from IP address 203.0.113.42
- Receiving Server Checks: The recipient's mail server performs a reverse DNS lookup on 203.0.113.42
- PTR Record Retrieved: DNS returns the hostname associated with that IP (e.g., mail.example.com)
- Forward DNS Verification: The receiving server then looks up mail.example.com to verify it resolves back to 203.0.113.42
- FCrDNS Check: If both directions match, the IP passes Forward-Confirmed Reverse DNS (FCrDNS)
- Reputation Impact: Passing FCrDNS improves email deliverability; failing it can result in bounces or spam filtering
Forward-Confirmed Reverse DNS (FCrDNS)
FCrDNS is a security measure that verifies both forward and reverse DNS match. It's one of the checks performed by mail servers to identify legitimate senders:
✓ Passing FCrDNS
IP: 203.0.113.42 → PTR: mail.example.com → Forward: 203.0.113.42 ✓ Match!
✗ Failing FCrDNS
IP: 203.0.113.42 → PTR: mail.example.com → Forward: 203.0.113.99 ✗ Mismatch!
Why PTR Records Matter for Email
- Spam Prevention: Many mail servers reject or flag emails from IPs without valid PTR records
- Required by Major Providers: Gmail, Outlook, and Yahoo all check PTR records for incoming mail
- Industry Standard: RFC 1912 recommends that every IP address used for email have a PTR record
- Reputation Signal: Proper reverse DNS indicates a professionally configured mail server
- Delivery Rates: Missing or mismatched PTR records can significantly reduce inbox placement
- Blacklist Prevention: IPs without PTR records are more likely to be blacklisted
Common PTR Issues
No PTR Record
The most common issue. Your IP address has no reverse DNS configured. Contact your hosting provider or ISP to set up a PTR record pointing to your mail server hostname.
FCrDNS Mismatch
PTR record exists but the hostname doesn't resolve back to the original IP. Ensure your mail server hostname has an A or AAAA record matching the IP.
Generic/Dynamic Hostname
PTR points to a generic hostname like "203-0-113-42.dynamic.isp.com" instead of a proper mail server name. This suggests a residential or dynamic IP and hurts deliverability.
Unusual Hostname
Hostname doesn't follow mail server conventions (e.g., missing "mail." or "smtp." prefix). While not critical, using standard naming helps establish legitimacy.
How to Set Up PTR Records
Step-by-Step Guide
- Identify Your Mail Server IP: Find the public IP address your mail server uses to send email
- Choose a Hostname: Select a proper mail server hostname (e.g., mail.example.com, smtp.example.com)
- Create Forward DNS Record: In your DNS panel, create an A record for mail.example.com pointing to your IP
- Contact Your Provider: Reach out to your hosting provider or ISP (they control reverse DNS zones)
- Request PTR Record: Ask them to create a PTR record for your IP pointing to mail.example.com
- Wait for Propagation: PTR changes can take 24-48 hours to fully propagate
- Verify Setup: Use this tool to check that both forward and reverse DNS match
- Test Email Delivery: Send test emails to major providers to verify improved deliverability
PTR Record Best Practices
- Use a descriptive mail server hostname (mail.yourdomain.com, smtp.yourdomain.com)
- Ensure the PTR hostname matches your HELO/EHLO greeting in SMTP
- Verify forward-confirmed reverse DNS (FCrDNS) is passing
- Use a static IP address for mail servers (not dynamic or shared)
- Match the PTR hostname to the domain in your email From: address when possible
- Avoid generic or ISP-assigned hostnames (e.g., "server123.hosting.com")
- Keep PTR records up to date if you change mail server IPs
- Monitor PTR records regularly as part of your email infrastructure
- If using multiple IPs, ensure each has its own proper PTR record
PTR Records vs Other Email Authentication
| Method | What It Checks | Required? |
|---|---|---|
| PTR | IP reputation and proper server configuration | Highly recommended |
| SPF | Authorized sending IPs/servers | Required |
| DKIM | Email content integrity and authenticity | Required |
| DMARC | Policy for SPF/DKIM failures | Required |
PTR records work alongside SPF, DKIM, and DMARC to establish your mail server's legitimacy. All four should be properly configured for optimal email deliverability.