550 5.7.25 Gmail: sending IP has no valid reverse DNS
Quick answer
Gmail rejected the message because the sending IP has no PTR record. Google requires every sender to have valid forward and reverse DNS. The temporary form of the same problem, including a PTR that does not match forward DNS, is 451 4.7.23.
Recommended action: Fix sender reputation
Common causes
- A new server or VPS whose IP still has the hosting company's default PTR, or none.
- A PTR hostname with no matching A or AAAA record.
- Sending over IPv6 from an address with no reverse DNS.
What to do
Set a PTR record for the sending IP in your hosting control panel, pointing to a hostname on your domain such as mail.example.com, and make sure that hostname resolves back to the IP. Check it with our Reverse DNS Lookup, then resend.
Provider note: This is about the sending server only. Every RocketVerifier verification IP passes forward-confirmed reverse DNS before it carries traffic.
How to read 550 5.7.25
550 is the basic SMTP reply defined in RFC 5321. 5.7.25 is the enhanced status code from RFC 3463, which reads as class, subject and detail:
- Class
- 5Permanent failure
- Subject
- .7Security or policy
- Detail
- .25Gmail: sending IP has no valid reverse DNS
Further reading
FAQ
Frequently asked questions
Who sets the PTR record?
The owner of the IP address: your hosting provider, cloud provider or ISP. Most hosting panels have a reverse DNS field for each IP.
Does 550 5.7.25 mean the recipient is invalid?
No. The recipient was never evaluated. Fix reverse DNS and the same address will accept mail.
Stop hard bounces before they start
Upload a list or call the API, and send only to addresses that can receive mail. Unknown results are always free.
100 free credits · No card required · Credits never expire