Troubleshooting the “Client Host Rejected: Cannot Find Your Hostname” Email Error in cPanel

If you’re seeing the error “450 4.7.25 Client host rejected: cannot find your hostname” in your logs when sending emails, it means the receiving server couldn’t verify your server’s hostname. This is often due to a missing or incorrect reverse DNS setup. In this blog, we’ll explain what causes this error and how you can fix it.

Understanding the error

The receiving email server cannot verify your server’s IP address with a valid hostname. You can resolve this by : 

• Check reverse DNS (PTR) record
• Test hostname resolution
• Verify IP is linked to your server
• Test SMTP connection
• Run cPanel diagnostic scripts
• Contact your hosting provider for setting up a valid PTR record

Steps to Resolve

1. Check your servers hostname resolution using:

dig hostname.yourdomain.com +short

You should perform this check from a different server to verify the setup. When you run the command, it should return your server’s IP address as the result.

2. Make sure the IP from the above command is bound to the your server by running the following on the server:

ifconfig | grep 198.xxx.xxx.xx

Replace the IP with your corresponding IP from the above command result. The result should be like:

[root@server ~]# ifconfig | grep 198.xxx.xxx.xx
 inet 198.xxx.xxx.xx  netmask 255.255.255.0  broadcast 198.xxx.xxx.xx
[root@server ~]#

3. Test SMTP connection by telnetting from another server. This will check if the server is responding to mail requests.

telnet hostname.yourdomain.com  25

Ensure the SMTP banner matches your hostname or main domain.

4. Use the cPanel-provided ‘cpdig’ script on the server to verify that the hostname resolves correctly and passes the validation check.

/scripts/cpdig hostname.yourdomain.com  A

/scripts/check_valid_server_hostname

5. If all the above steps worked correctly, then the issue is likely with your PTR (reverse DNS) record; to verify this, run the following command from another server and check the output:

nslookup 198.xxx.xxx.xx

The result should be like:

[root@server ~]#nslookup 198.xxx.xxx.xx
228.x.x.x.in-addr.arpa    name = hostname.yourdomain.com

Authoritative answers can be found from:
[root@server ~]#

If the command returns your hostname, then the PTR record is correctly configured; if it returns something else, you’ll need to contact your data center or hosting provider and ask them to update the PTR record to point to your correct hostname.

Conclusion:

The “450 4.7.25 Client host rejected: cannot find your hostname” error is usually caused by a missing or incorrect reverse DNS (PTR) record. While it might seem technical, the issue can often be resolved by checking your server’s hostname, DNS settings, and SMTP configuration. By following the steps outlined above—or contacting your hosting provider for assistance—you can quickly restore normal email delivery and avoid future rejections.

If you’re still facing the 450 4.7.25 Client host rejected: cannot find your hostname error or struggling to configure your mail server in cPanel, our expert cPanel Server Management Services team is here to help. We provide 24/7 professional support to diagnose and fix email delivery issues, optimize server settings, and ensure your hosting environment runs smoothly. Contact us today and get your emails working without interruptions.