Its abandoned, I tried Blacklist and its not the same (+ I think it isn't working), anyone got a good suggestion? google shows Heroes but it seems broken too, thank you in advance for the reply.
In specific I want an addon that I could tell someone its blacklisted in the style of DIKY's !! sign on chat and tooltip warning.
I use Badapples, though it only handles the "blacklisting" part of what DoIKnowYou does. You add someone to your "bad apples" list, and then you're warned when you (1) send a whisper to them, (2) receive a whisper from them, (3) join a group they are in, or (4) are in a group and they join it. It also colors their name in tooltips, and in chat, though other addons may override one or both of those features.