Reverse DNS (PTR) lookup
Enter the IP address of the server that sends your mail. We look up its PTR record and check that the name points back to the same IP, as Gmail requires.
The address is only used for the lookup: it is not stored or logged.
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How it works
What reverse DNS is
Normal DNS turns a name into an IP address. Reverse DNS does the opposite: the PTR record of an IP gives its name. Receivers use it to check that a mail server is what it claims to be.
Forward-confirmed
A PTR name only counts when that name also resolves back to the same IP. Gmail rejects mail from IPs that fail this test with the error 550 5.7.25.
Who can fix it
The PTR record belongs to whoever owns the IP address: your hosting company or email provider, not your domain's DNS. Set it in their control panel or ask their support.
Questions
Which IP should I check?
The public IP of the server that sends your mail. It is in the headers of a message you sent, in the Received line written by the receiving server: the email header analyzer shows it.
My PTR name looks like ip-203-0-113-7.provider.net. Is that a problem?
Gmail accepts it as long as it points back to the IP, but some receivers trust automatic names less. A name on your own domain, such as mail.yourdomain.com, is better.
I send through Google Workspace, Microsoft 365 or Mailjet. Do I need a PTR?
No: their servers already have one. Reverse DNS matters when you run your own mail server, or send from a VPS or a dedicated IP.
Do you keep the IP addresses I check?
No. The address is used for the DNS lookup and then discarded: it is not stored, not logged, and never part of the page address.
Related guides
- What Is a PTR Record? Reverse DNS Explained for EmailA PTR record maps an IP address back to a name. How reverse DNS works, why mail servers check it, how to look it up, and where to set it at your host.
- 550 5.7.25: Gmail \"The IP Address Sending This Message Does Not Have a PTR Record\"550 5.7.25 means Gmail rejected your email because the sending IP has no valid reverse DNS (PTR) record. How to check it and who can fix it.
- Email Headers: How to Read Them, Line by LineWhat email headers are, how to open them in Gmail and Outlook, and how to read the Received, Authentication-Results, DKIM and Return-Path lines.
- Gmail, Yahoo and Outlook Sender Requirements in 2026: The Complete ChecklistWhat Gmail, Yahoo and Microsoft Outlook require from email senders in 2026: SPF, DKIM, DMARC, spam rate limits and one-click unsubscribe, with a setup checklist.