The proxy chat allows you to store and filter all the chat protocols that are routed by the CM. You can catch MSN chat, YAHOO, JABBER and others (check the manual). To enable it go to Security → Proxy → Proxy chat.
If the default_input rule in firewall is configured to DROP, you must add a rule to allow the proxy chat traffic. The parameters for the firewall rule are the following:
name: ProxyChat
Priority: first
Type: input
Input interface: all
Traffic: x Custom;
x Transport procotol: tcp;
x Destination port:
x unique: 16667
Action: accept