[Spinball]

Originally Posted by lifesourcerec

Dunno if this is already a feature or not, but how can you make:

Specific URL mandatory and somehow make it where that a link a\can only be used twice (one time for each involved).

I think this is a very good idea. You could even go one step further and make it so that the link to leave feedback is only available on trading threads and automatically refers to that thread.
On our forums it is against the rules to negotiate via PM since the mods can't see what's going on and then can't adjudicate should a problem occur. Only private details are passed via PM.
Forcing people to refer to a thread when leaving feedback would mean that unless they cheat and put in an unrelated thread (risking a ban) they must refer to a thread and therefore can't use PMs to trade.