Clientside session/soft blacklist

Could it be possible to have secondary soft blacklist, or session blacklist, however to call it. It would be to blacklist people we find offending which clears automatically, either being just session based, or timed for few days. Being stored on the client side it wouldn't increase the character's server footprint. Purpose, for most part, gold sellers and other such malcontent which goes through names on daily basis. Adding them to blacklist is necessity for peaceful existence, but keeping the blacklist clear of them as they go is daunting. This way the blacklist could serve for more measured needs, such as arise in social game.