Gmail 550 5.7.25
Blocked: missing PTR record
Gmail 550 5.7.25 means: blocked: missing PTR record. It is a permanent failure, so do not retry it unchanged. The sending IP needs a PTR record whose name resolves back to the same IP. Set it with your hosting or sending provider.
Gmail’s exact wording
Quoted from Google Workspace Admin Help: Gmail SMTP errors and codes, checked 2026-11-05. Placeholders are Gmail’s own.
Reply text
This message was blocked because the sending IP address doesn't have a PTR record, or the forwarding DNS entry doesn't reference the sending IP address. Gmail requires that sending IP addresses have a PTR record. Learn more about requirements for sending IP addresses. To learn more about Gmail requirements for bulk email senders, visit Email sender guidelines.
| Who sends it | Gmail and Google Workspace |
|---|---|
| Basic code | 550: Requested action not taken: mailbox unavailable (e.g., mailbox not found, no access, or command rejected for policy reasons) (RFC) |
| Enhanced code | 5.7.25: Reverse DNS validation failed |
| Permanent or temporary | Permanent (5xx) |
| Verifying the list prevents it | No |
In practice
Gmail blocks mail from IPs without a valid PTR record. The PTR must resolve to a hostname whose A or AAAA record points back to the same IP, called forward-confirmed reverse DNS. Most sending services manage this. If you run your own server, set the PTR to your mail hostname, and make the HELO name match.
What the sender should do
The sending IP needs a PTR record whose name resolves back to the same IP. Set it with your hosting or sending provider.
Would verifying the list have prevented Gmail 550 5.7.25?
No
This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
Common questions
- What does Gmail 550 5.7.25 mean?
- Gmail 550 5.7.25 means: blocked: missing PTR record. It is a permanent failure, so do not retry it unchanged. The sending IP needs a PTR record whose name resolves back to the same IP. Set it with your hosting or sending provider.
- Should I retry after Gmail 550 5.7.25?
- No. It is a permanent (5xx) failure, so the same message to the same address will fail again. Fix the cause first. The sending IP needs a PTR record whose name resolves back to the same IP. Set it with your hosting or sending provider.
- Would verifying my list have prevented Gmail 550 5.7.25?
- No. This reply is about your sending setup, the message or the receiving system, not about whether the address exists, so verifying the list will not prevent it.
The same code elsewhere
Sources
- Google Workspace Admin Help: Gmail SMTP errors and codes (checked 2026-11-05)
- IANA: SMTP Enhanced Status Codes registry (checked 2026-11-05)
- RFC 5321: Simple Mail Transfer Protocol, section 4.2.3 (reply codes) (checked 2026-11-05)
Registry and provider wording is quoted exactly; guidance is written by the SimpleVerifier Team.
SimpleVerifier Team · Last checked against the sources 2026-11-05