Interesting proposition, but too blanket of a policy to be a long-term solution.

Email is the biggest problem to those who not only receive large amounts (100+) but also have to spend large amounts of time coordinating responses to those emails (it is not quantity of email received, but complexity of replies that drives email overload). Shutting it off to everyone removes a valuable communication channel that, while often abused, is important in the workplace.

One of the best things a company could actually do IMO if they wanted to mandate an experiment, is to have everyone chunk their email checking and responding times. Studies have shown doing so, checking for example 6 times a day, greatly reduces context-switching losses and reduces time taken to complete primary tasks.