The cloud is supposed to be "push button receive bacon", and in practice I have found Office 365 to be anything but.

Microsoft's cloudy email offering does basic email very well. You can buy a licence for a new user with ease, set up an email address for them and connect up your client of choice. A few clicks and email starts flowing; it just works. But it's 2012. At this point, sendmail "just works" too, and it ships with virtually every Linux distribution known to man. You can even download fully operational real-boy mail servers as virtual appliances, put them on VMWare's freebie ESXi, and then build them into a wall. They'll run for the next decade or so without you having to fret about them.

Sendmail, however, has the added bonus of supporting certain highly demanded features like mail merges; Office 365 places severe restrictions (that you cannot control or change) on the amount and frequency of outbound mail. This makes running the corporate newsletter a no-go.