RBL Failure: error open resolver

Using RBLs (remote block lists) can be a great way to reduce incoming spam on your server. However, the configuration of your email server is important for keeping email flowing correctly. If you use cPanel, you may have run into a situation where all incoming emails are being rejected as spam. If the error you encounter is “error open resolver” when using the RBL from Spamhaus, the problem may be that you are using a public dns resolver for your email server.

Check the following settings to fix this configuration issue.

1. Review /etc/resolv.conf on the server to ensure that Exim is using a private resolver. By default, Liquid Web servers are designed to use Liquid Web’s private resolver at 10.10.10.10. Using a public resolver (even Google’s) could cause this problem.
   
   For example, this server is using Cloudflare’s public dns resolver (1.1.1.1):
   
   :generated by /usr/sbin/dhclient-script
nameserver 1.1.1.1
   
2. Remove any public dns resolvers and only use private dns resolvers (like Liquid Web’s dns resolver).
   
   :generated by /usr/sbin/dhclient-script
nameserver 10.10.10.10

If you still see problems with incoming email delivery, reach out to our Support Team for additional help.