Blind FC invites are very annoying. The chances are that any FC that spams out invites to anyone who happens not to be in a FC is not really worth joining in the first place. When I created a character I was literally invited by the same person over and over again. I wised up and just ignored the invite, letting the timer run through. I should not need to blacklist people to stop them inviting me.

I do however think that using the "busy" status stop the invites? Not sure though. Maybe someone can confirm? Though this is hardly an elegant solution.

Really need a setting in prefs to block FC invites and while they are at it add one in for block trade requests.