Actually, push and pull in the case aren't all that different. Using a reflector address, the system could send a single message to each server.
Ideally each server has more than one user and if a distributed system looks anything like our current email infrastructure, there are would only be a handful of large service providers, each with millions of users.
Of course, there might be thousands of followers also using smaller providers, but sending a few thousand emails is not a big deal (and not that much different from a few thousand providers pulling from a central hub).
Ideally each server has more than one user and if a distributed system looks anything like our current email infrastructure, there are would only be a handful of large service providers, each with millions of users.
Of course, there might be thousands of followers also using smaller providers, but sending a few thousand emails is not a big deal (and not that much different from a few thousand providers pulling from a central hub).