# SMTP: 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

**Code:** `550 5.7.25 PTR record required` · **Category:** Email / SMTP · **Seen on:** SMTP, Linux

Gmail (and others) require your sending IP to have a reverse DNS (PTR) record that resolves back to the same IP; yours has none or it does not match.

## Meaning

A PTR record maps the IP to a hostname; the hostname's A record must map back to the same IP (forward-confirmed reverse DNS). Only the owner of the IP block (hosting provider/ISP) can set the PTR. Use a hostname that matches your HELO/EHLO name.

## Common causes

- No PTR record for the sending IP
- PTR exists but its hostname's A record points elsewhere
- Generic ISP PTR (e.g. 203-0-113-5.isp.net)
- HELO name differs from the PTR
- Sending from a cloud IP without configuring rDNS

## Quick fix

1. Ask your host to set the PTR to mail.example.com
2. Create the matching A record for the same IP
3. Set Postfix `myhostname = mail.example.com` so HELO matches

## Detailed fix by platform

### Linux

1. `dig -x 203.0.113.5 +short` then `dig +short mail.example.com` — both must agree

### Postfix

1. `postconf -e 'myhostname = mail.example.com'; postfix reload`

## How to diagnose

1. **PTR** — Does `dig -x IP` return a name?
2. **Forward** — Does the name resolve back to the IP?
3. **HELO** — Same as PTR?

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Source: [WhatIsMyError](https://whatismyerror.com/errors/email/550-5-7-25-ptr-record-required)