I wish deckbox would do more to address the issues of traders who don't respond to offers. Perhaps a biweekly email sent to any member who has pending trade offers that they haven't responded to? Maybe if a member has offers they haven't responded to, then they can't initiate new trade offers?
Seems unnecessary to harass/punish unresponsive traders - that would likely just turn them off from the site as a whole.
Proposing a configuration already notifies them. You can also send them messages that go to their email. Yeah, not responding is kinda annoying but I think there's more to lose than gain by trying to force responses.