(5/5)
The documentation's inside the file. It explains what the addon's job is and how to contact the author. Maybe it's better to explain how to use it, although it's pretty easy.

    (3/5)
The Addon works fine. It uses "On Open" event and asks for approval before getting the msg. If you decline a msg, the addons ignores the user. You can set the time of the ignore.
 
* It would be great to set the ignore time to some default.
 
In my opinion, a user which gets my approval won't need to get it again tomorrow, so it's better to save somewhere those users which get your permission already.

    (3/5)
As I said, set the ignore time to some default.
Try to think about making a list for users you already know to block them, and another list to those who are approved.
I suggest to make an "on unload" event to unset the variables used for the addon.

Nice addon, Personally I think it'll drive me crazy after an hour or so. Try to fix it, so it'll be a more usefull blocker.
GJ.