Maybe one could prioritize the messages in the inbox, and assign a lower priority if the sender has contacted more people in a reference time frame (eg last 7 d

Maybe one could prioritize the messages in the inbox, and assign a lower priority if the sender has contacted more people in a reference time frame (eg last 7 days). That way people that mass-mail others get ignored pretty much automatically. Of course that system also has its downsides, it encourages creating multiple accounts.