As explained in the FAQ:
'You are connecting from a known proxy' What does this mean?
This means your IP address is flagged by a spam-monitoring website. You are likely trying to connect through a proxy to the server, but false positives do happen.
This is a security measure which was put in place to prevent bots using proxies to connect to the server.
If you're receiving this message, there's nothing to worry about. The only thing needed on your behalf is to create a ban appeal explaining your situation, the rest will be sorted and your ban will be lifted.
The IP will need to be unblocked by Optical, I've made him aware of this.