Re: MS Exchange?
I wonder if that is the biggest email deployment in the world that isn't an ISP or webmail provider?
In the list of world's largest employers:
US Department of Defense[sic] That one could be larger, but they are spread over loads of .mil and .gov domains, so maybe each one has a separate email service? Also, I don't know if all the regular squaddies have email addresses.
People's Liberation Army Again, the regular squaddies probably won't have email addresses.
Walmart The likes of asda.com (their UK operation) will presumably be on a separate email service, and checkout operators, shelf stackers, warehouse operatives, cleaners and so on probably won't have email addresses.
McDonalds Only the largest if you include the employess who work for franchises, and the burger flippers probably won't have email addresses.
NHS is 5th on the list. Just over half the employees are admin staff, and they will all have email addresses. The clinical staff and most maintenance staff will also need to use email. That leaves the likes of the cleaners, hospital porters and catering staff who maybe don't need email.