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Bounce error codes · Gmail and Google Workspace

Gmail 550 5.7.25: no PTR record for the sending IP

Gmail requires every sending IP address to have reverse DNS that points to a hostname, and that hostname to point back to the same IP. Yours doesn't.

The exact error texts

  • 550 5.7.25 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.

  • Temporary version

    451 4.7.23 The sending IP address for this message doesn't have a PTR record, or the PTR record's forward DNS entry doesn't match the sending IP address. To protect users from spam, your email has been temporarily rate limited.

  • Sending over IPv6

    550 5.7.1 This message does not meet IPv6 sending guidelines regarding PTR records and authentication. For more information, go to Email sender guidelines.

Quoted from Google Workspace — Gmail SMTP errors and codes

Check your domain

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What Gmail checks

Google's requirement, for all senders: the public IP of the sending server must have a PTR record that resolves to a hostname (reverse lookup), and that hostname must have an A record (IPv4) or AAAA record (IPv6) that resolves back to the same IP (forward lookup). If either half is missing or they don't match, you get 5.7.25, or 4.7.23 while Gmail only rate-limits.

LookupExampleMust return
PTR of the IPdig -x 203.0.113.10A hostname, e.g. mail.example.com
A / AAAA of that hostnamedig mail.example.comThe same IP, 203.0.113.10

Who can fix it

A PTR record lives in the reverse DNS zone of the IP range, which belongs to whoever owns the IP, not in your domain's DNS. Adding a record in your DNS panel won't fix it.

  • VPS or cloud server: most providers let you set reverse DNS in their control panel, or do it on request. Set it to a hostname whose A/AAAA record points back to the server.
  • Office or home connection: the ISP controls it. Most residential IPs shouldn't send mail directly: relay through your mail provider instead.
  • Email provider or sending service: their IPs should already be correct. If they're not, it's their problem to fix. Open a ticket with the bounce.

Checking it yourself

  1. Get the sending IP: it's in the bounce, or paste a delivered message's headers into the header analyzer.
  2. Run dig -x <ip> +short in a terminal, or use Google's Admin Toolbox Dig (PTR).
  3. Run dig <hostname> +short (add AAAA for IPv6) on the result and compare.

Sending over IPv6? Gmail's IPv6 variant of this rejection (550 5.7.1) also mentions authentication: make sure the IPv6 address has a matching PTR and that SPF covers it.

PTR records belong to IP addresses, so the domain check above doesn't test them. It does check SPF, DKIM and DMARC, which Gmail looks at next.

Questions

Can I add a PTR record in my domain's DNS?

No. Reverse DNS is controlled by the owner of the IP address block: your hosting company, cloud provider or ISP. You choose the hostname; they publish the record.

Does the PTR hostname have to be my domain?

Google recommends reverse DNS that points to your domain. What 5.7.25 itself checks is that a PTR record exists and that its hostname resolves back to the same IP.

Is this only for bulk senders?

No. Valid forward and reverse DNS is in Google's requirements for all senders, whatever the volume.

Why did it start after moving my server?

A new IP comes with no PTR record or the old provider's generic one, which doesn't resolve back to your hostname. Set reverse DNS on the new IP before sending.

Sources

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