That's nice, but as a business decision the wikimedia foundation has decided to host our corporate email with Google. For personal mail we all have the choice of whatever system we would like, but this business decision has been made for us, and if someone wants a wikimedia.org address, I don't think it's an onerous burden to require that they use our current infrastructure to access it, instead of requiring us to do a lot of difficult workarounds. Unless I've missed something, using wikimedia.org for non-employees is a option, not a necessity.
It was my understanding that part of this discussion was to require volunteers to use a specific mail server to post to the list....but now I can't find the message that gave me that impression, so maybe I've misunderstood the nature of the thread?
(I'm leaving out arguments about the decision to host with Google, but it seems like a relevant thing, perhaps there are archived discussions that I could read?)