Message rejected by Mail-List.com 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, Mail-List.com will reject the email.
To verify the mail server is set up correctly, use tools like:
- Host lookup failed (220.127.116.11 does not match any IP address for mail.example.com)
While waiting for the ISP to fix this problem, send a message to the Mailing List directly from your Mail-List.com account.
Follow the step-by-step instructions in this post: Send a message to the List.