550 5.7.25: no PTR record, blocked
Gmail rejected the message because the sending IP has no reverse DNS record, or the hostname in that record does not point back to the IP.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 550 5.7.25
- Provider
- Gmail and Google Workspace
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
550 5.7.25 This message was blocked because the sending IP address doesn't have a PTR record…
What it means
Gmail requires every sending IP to have a PTR record whose hostname resolves forward to the same address. This is the permanent form of that requirement; the temporary one is 451 4.7.23. Google lists the code in its sender guidelines FAQ among those it sends when a requirement is not met. The fix sits first with whoever controls the IP's reverse DNS, which is your hosting or cloud provider in most setups, and then with the A or AAAA record for the hostname in your own DNS.
Common causes
- The sending IP has no PTR record.
- The PTR hostname does not resolve back to the sending IP.
- Mail leaves through an IP that was never given reverse DNS.
How to fix it
- 01Look up the sending IP with a PTR lookup.
- 02Ask your hosting or cloud provider to set a PTR record pointing to a hostname you control.
- 03Add an A or AAAA record for that hostname pointing back to the same IP.
- 04Resend once both records resolve.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
- Email sender guidelines FAQ (Gmail Help)support.google.com
- Email sender guidelines (Gmail Help)support.google.com
Related codes
- 451 4.7.23No PTR record, rate limited.Gmail is rate limiting mail from your IP because its reverse DNS record is missing or does not resolve back to the same address.
- 421 4.7.0No PTR record for the sending IP.Gmail is rate limiting mail from your IP because it has no reverse DNS name, or that name does not point back to the same IP.
- 550Mailbox unavailable.The receiving server permanently refused the message for this recipient: the mailbox does not exist, cannot be reached, or the server rejected the message by policy.
- 550 5.7.25Reverse DNS check failed.The sending server's IP address failed the receiver's reverse DNS check, usually because it has no PTR record or the PTR name does not lead back to the IP.
5.7.25 at other providers
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce