You want to filter or block instant messaging programs.
K9 Web Protection currently does not filter the protocols used by instant messaging programs such as MSN, AOL, Yahoo, ICQ, etc. This is a feature that we would like to add to K9 at some point, but we do not have any information on when this feature might be available. However, with continued support and use of K9, we will be able to add more features.
Please note that blocking the "Chat/Instant Messaging" category under "Custom" protection level will prevent users from accessing web pages offering the ability to chat with others on the internet or download those programs, but will not affect instant messaging programs that you install on your computer.