How to stop an open relay on the Qube?
Here is what you should check: 1. Email | Email Servers | Advanced | Relay Email From Hosts/Domains/IP Addresses – Should have your IP address range in it along with your domain name. 2. Email | Email Servers | Advanced | POP Authenticated Relaying – might be a good idea for you, users have to check mail before sending. 3. From the Command line (Telnet or SSH) – Find out if port 3128 is open. Use the nestat -a command and see if any of the foreign addresses are using 3128. If they are, they must be locked down. The quickest way to fix your problem might be just turning off web caching, but I recommend enabling your firewall and stopping 3128 from the outside.
