I worked as a service developer at a large telco in Europe, building - among other things - mail infrastructure. If there was one thing I would not have uttered in that context it would have been '...proper e-mail usage ... through MS Exchange'. We fought tooth and nail to be able to have 'proper email' despite the insistence of corporate to use MS Exchange. In the end we ended up with two machines on each desk, one of them for the sole purpose of communicating with those parts of the company which used MS Exchange.

Things might be less bad nowadays, I don't know. What I know about MS Exchange is enough to keep away from it.