This plugin is designed to prevent on-the-spot griefing. It works by protecting each block on placement. No messy setting points, protecting more area then required, and no heading into the middle of nowhere to protect some random player's house! This means you can have players running around your server building things without worry of griefers destroying their stuff as they build it.
The plugin has three ListModes. The first is simply "None", which means any player who builds has their blocks protected and other players are unable to destroy them with the exception being OPs (configurable in the perms). Setting the ListMode to "None" or anything besides "WhiteList" or "BlackList" will put it in "None" mode. When a player destroys their own block, anyone can build there and once someone does, the block is protected under that new player.
The second ListMode is "BlackList". This allows OPs to add or remove players from a list. Under BlackList, the player is allowed to build freely and such but their blocks are not protected. You can also add a player to the list to deprotect their blocks. However if they're added to the BlackList and the removed from it, any remaining blocks belonging to the player are re-protected.
The third ListMode is WhiteList. This mode turns off protection for everyone (even OPs) unless they're on the WhiteList. Adding a player to this list will protect their blocks as they build and only they or an OP will be able to destroy their blocks. Removing a player from the WhiteList will unprotect their blocks, but if you add them to it again, any remaining blocks placed by them will become protected once again.
The reason re-adding someone to the WhiteList, or re-removing them from the BlackList protects their blocks once again is because this plugin handles protection on a per-block basis, and I'm unable to remove all protections for them without burning through a ton of system resources.