A lot of people seem to voice a disdain for Notes but I actually liked it for some reason.
I saw at least one large company that migrated from Notes to exchange and they got the email/calendaring bit done quite easily and were still running notes servers for line of business applications years later.
It felt like they basically tacked on the email functionality to to Notes to sell it, but it always seemed kinda ok to me.
Let's revisit this when it's Reply to Reply to Reply to Reply :)