Enhanced Status Code 5.7.25: Reverse DNS Validation Failed

Permanent failure High severity Security RFC 7372

What it means

Enhanced Status Code 5.7.25 means “Reverse DNS Validation Failed.” Your sending IP address does not have a valid reverse DNS (PTR) record, or the PTR record does not match the forward DNS. Google requires all senders to have valid forward-confirmed reverse DNS (FCrDNS) on their sending IPs.

At a glance

Code5.7.25

Bounce typeHard (permanent)

SeverityHigh

CategorySecurity

What to doSuppress the address; do not retry

StandardRFC 7372

What it looks like in your mail logs

550 5.7.25 The IP address sending this message does not have a PTR record setup, or the corresponding forward DNS entry does not point to the sending IP. As a policy, Gmail does not accept messages from IPs with missing PTR records.

What does 5.7.25 mean?

Enhanced status code 5.7.25 means the receiving server checked the reverse DNS (PTR record) of your sending IP address and found it missing, invalid, or not matching the forward DNS lookup. This is a critical configuration requirement.

Google requires all senders to have a valid PTR record for their sending IP. The PTR record must resolve to a hostname, and that hostname must resolve back to the same IP (forward-confirmed reverse DNS / FCrDNS). Microsoft and Yahoo also check reverse DNS as part of their sender validation.

If you are using a dedicated IP for sending, work with your hosting provider or ESP to ensure proper PTR records are configured. If you are on a shared IP, your ESP should have this configured already - contact them if you see this error.

How 5.7.25 plays out

Your server attempts delivery

The recipient server returns a permanent 5.7.25 rejection

This is a hard bounce: the message will not be accepted as sent

Suppress the address and fix the root cause before resending

Where 5.7.25 sits: soft vs hard bounce

	Soft bounce (4xx)	Hard bounce (5xx)
Nature	Temporary	Permanent
SMTP class	`4xx`	`5xx`
What to do	Let it retry	Suppress the address
Recoverable?	Often	No
5.7.25 is		✓ this code

Common causes of 5.7.25

No PTR record configured for the sending IP address
PTR record hostname does not resolve back to the sending IP (FCrDNS failure)
PTR record points to a generic hostname (e.g., 123-45-67-89.host.com)
DNS propagation delay after PTR record changes
Hosting provider has not configured reverse DNS for your IP

How to fix 5.7.25

Configure a PTR record for your sending IP through your hosting provider
Ensure the PTR hostname resolves forward to the same IP (FCrDNS)
Use a professional hostname for PTR, not a generic one (e.g., mail.yourdomain.com)
Verify with our Reverse DNS Checker tool
Contact your ESP if using a shared IP - they should have this configured

Frequently asked questions

What does error 550 5.7.25 mean in Gmail?

Error 550 5.7.25 means the IP address sending your email does not have a valid PTR (reverse DNS) record, or the PTR record does not match the forward DNS entry for that IP. Gmail requires all sending IPs to have a properly configured PTR record and will reject messages from IPs that lack one. This is a strict Gmail policy designed to verify that the sending server is legitimately associated with a domain.

How do I set up a PTR record to fix 5.7.25?

Contact your hosting provider or ISP; PTR records are set by the owner of the IP address block, not through your domain registrar. Ask them to create a PTR record for your sending IP that maps to your mail server's hostname (e.g., mail.yourdomain.com). Then ensure that hostname has a matching A record pointing back to the same IP. This forward-confirmed reverse DNS (FCrDNS) is what Gmail validates. Changes typically propagate within 24 to 48 hours.

Why does Gmail reject email with "no PTR record" but other providers accept it?

Gmail enforces stricter sending infrastructure requirements than most other email providers. While Microsoft 365 and Yahoo also prefer valid PTR records, Gmail is one of the few providers that will outright reject messages at the connection level if no PTR record exists. This policy is part of Gmail's bulk sender guidelines and applies to all senders, not just high-volume ones. Other providers may accept the message but factor the missing PTR into spam scoring instead.

Does 5.7.25 affect IPv6 email delivery?

Yes, IPv6 addresses require PTR records just like IPv4 addresses. Gmail rejects mail from IPv6 addresses that lack PTR records, and you also need a matching AAAA record for the forward lookup. Many hosting providers do not automatically configure IPv6 reverse DNS, so if your server sends mail over IPv6, explicitly verify that both IPv4 and IPv6 PTR records are in place. If IPv6 reverse DNS is not available from your provider, disable IPv6 sending for your mail server.

Related bounce codes

Sources & further reading

RFC 7372 · The standard that defines this reply code Google Workspace Admin Help · Email sender guidelines requiring valid forward and reverse DNS (PTR) records on sending IPs

Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026 ← All bounce codes