There’s a difference between technically sound and supported.  The following story from a Texas Healthcare provider illustrates the difference.  The comments in response to the story are actually more interesting than the story.

“Their (Microsoft’s) words were ‘while it is legally and technically feasible, Microsoft has chosen not to provide support for such a configuration (Exchange on Azure) at this time and has documented this.’ We backed out of an agreement on Azure, costing us $30,000 in losses, delays, and increased risks.”

Azure cloud support shock for Texas healthcare provider