550 5.7.25 Gmail bounce: no PTR record
What 550 5.7.25 means
Gmail blocked the message because the sending IP has no valid PTR record that matches forward DNS.
Message text
This message was blocked because the sending IP address doesn't have a PTR record, or the forwarding DNS entry…
This is an excerpt: the provider's documentation shortens the message. Full text: provider documentation
Common causes of 550 5.7.25
- No PTR record for the sending IP
- PTR record does not forward-resolve to the same IP
How to fix 550 5.7.25
- Run reverse DNS lookup on the sending IP.
- Set a PTR whose hostname resolves back to that IP.
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How to read 550 5.7.25
The first part, 550, is the SMTP reply code. Requested action not taken, mailbox unavailable: the mailbox does not exist, is not allowed, or the message was refused for policy reasons. Replies that start with 4 are temporary and replies that start with 5 are permanent (RFC 5321 §4.2.1).
The second part, 5.7.25, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 7 is security or policy: authentication, authorization or policy refused the message. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.
Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.
Official source: knowledge.workspace.google.com. Last verified 2026-10-20.
Related guides
- Reverse DNS (PTR) for mail servers: how to set it
- How to create an SPF record (syntax and examples)
- How DKIM works and how to publish a DKIM record
Related codes
- 5.7.25 SMTP: reverse DNS failed
- 5.7.25 Microsoft: IPv6 needs reverse DNS
- 5.7.0 SMTP: security status
- 5.7.1 SMTP: delivery not authorized
- 5.7.23 SMTP: SPF validation failed
- 5.7.26 SMTP: authentication failed
FAQ
What does 550 5.7.25 mean?
Gmail blocked the message because the sending IP has no valid PTR record that matches forward DNS. This is a permanent failure.
How do I fix 550 5.7.25?
Run reverse DNS lookup on the sending IP. Set a PTR whose hostname resolves back to that IP.
Is 550 5.7.25 permanent, and should I retry?
550 5.7.25 is a permanent failure, so retrying the same message will fail again. Fix the cause first, then send a new message.