User Manual*** Welcome to's User Manuals! ***Email Discussion Group - List Owner Manual TroubleshootingMessage rejected by because Sender does not have Reverse DNS setup.

Message rejected by because Sender does not have Reverse DNS setup.

Reverse DNS is a critical step in authenticating email senders. All legitimate senders of email have this properly configured. Reverse DNS means the name of the host server sending the email matches the IP address it is sending from. See this Wikipedia post for more information.

If not configured correctly, will reject the email.

To verify the mail server is set up correctly, use tools like:

Common error messages in this situation.

  • Host lookup failed ( does not match any IP address for


How do I fix this problem?

You need to work with your upstream ISP to resolve this issue.

Your ISP has assigned you the IP address. They need to update that IP address in this field to point to your mail host name.

When you file a support ticket with the ISP, be sure to provide them with any error messages.

I need to send a message to my List "right now".

While waiting for the ISP to fix this problem, send a message to the Mailing List directly from your account.

Follow the step-by-step instructions in this post: Send a message to the List.