Microsoft Office 365 - If you think moving your domain over and connecting the pieces between Outlook, Office Web Apps, and SkyDrive on your own is a little kludgy, Office 365 is $6/user per month, adding up to $72/user per year and comes with a ton of features. If it's just email and shared calendars you want, you can use their $4/user per year ($48/user per year) plan and leverage Office Web Apps and SkyDrive for free.

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