Even if you ignore the multitude of problems raised by funneling all email through one company this suggestion is dead on arrival. Can you imagine mailing lists via a twitter like platform, e.g. debian-devel or lkml? I do not think debian or kernel development would be what it is today if twitter was the communication medium of choice. Vulnerabilty submissions to @microsoft-security?

I am surprised that this idea made it to the front page of HN.