NOTE: BukkitDev may mark this as inactive. This is most likely incorrect as the plugin is at a point in which it does not need to be improved on and will only require an update if a change in the BukkitAPI breaks it.
This plugin adds some missing functionality to the vanilla whitelist commands. When using the "on", "reload", or "remove" arguments, any players that are not whitelisted that are on the server will be kicked with a message saying, "You are not white-listed on the server".
There are no commands, permissions or configuration files to mess with. Simply drop the file into your plugins folder and reload/restart your server.
https://github.com/Musician101/WhitelistFix
Before you ask me to update to a specific build, here are some things to consider:
Do NOT message me unless I ask you to.
I do have a Twitter Account should something happen.
Otherwise, you can submit a ticket with the proper information and I might able to help you out.