I would caution against that going too far with that last part.

When I read "invitation" system, I'm thinking of a mechanism whereby an existing user can generate a one-time-use token which enables account creation. It's a gating/throttling mechanism.

When you propose a traceback method that punishes the source of the token, then you are asking the existing user to vouch for the new user. This is a much higher bar.

With an invite token system, I could hand out a MemeStreams access card to someone I'd just met -- at a party, or a technical conference, on the airplane, whatever. These are opportunities where the site could branch out to reach entirely new audiences, as opposed to just adding one more person within the same circle of friends. But if I was expected to personally vouch for every one of these new users, none of them would receive an access card.

I see your point. We would put a layer of common sense on top of it though.. If a chain of spammers came back to a user that was actually an active member of the community, we obviously wouldn't delete them. If a user was regularly giving out invites to spammers, we would take their ability to give out invites rather than deleting them if they were not spamming themselves.

At this point, I'm getting push-back on doing the invite system thing, so it's unlikely I'm going to sit down to code it up anytime soon..

RE: Registration temporarily disabled