It would be nice if Apple could see the enterprise uplift their server offerings. Apple doesn't seem to push OSX Server has hard as they could. Mail could be a viable contender to Exchange if they put more resources and marketing behind it.
funniest thing i've heard. i used to be an Exchange Admin, there is nothing that can come close to being half as good as MS Exchange. POP3/IMAP might be good enough for internet mail or college students, but not an organization where PHB wants the email managed.