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Gmail

550 5.7.25 “doesn't have a PTR record”

The IP address that sent your mail has no reverse-DNS name, or that name doesn't point back to the same address. Gmail requires both for every sending address.

Codes: 550 5.7.25 or 451 4.7.23. Source: Google Workspace: Gmail SMTP errors and codes.

What usually causes it

  • A self-hosted mail server on an address whose reverse DNS was never set.
  • Mail sent straight from a home or office connection instead of through a mail service.

How to fix it

  • Ask whoever owns the IP address (your hosting company or internet provider) to set its reverse-DNS name, for example mail.example.com. This is set in their control panel, not in your DNS.
  • Make sure that name has an A (or AAAA) record pointing back to the same address.
The free email check can find part of this

The free check tests reverse DNS for addresses named in your SPF record and for your mail servers. An address that sends but isn't named in SPF needs a real message's headers.

Run the free email check

Want it fixed? Our email deliverability packages start at $49 for an audit and plan. Other error codes.