Thanks to some very hard working MS employees for working on this awesome tool for many months and now releasing to the web for testing. This tool is extremely useful to South African organisations, as it allows you to calculate how much bandwidth is required to run your organisation’s email requirements against Exchange Online (Office 365).
It is extensive and takes into account various types of user profile and various email clients e.g. Outlook, Outlook Web Access and an array of mobile devices (through Active Sync) which could be used.
Hop on over to the Exchange Server team's blog to download the tool and understand how it works.
Remember, the output is only as good as in the input.
PS – yes, this is also works for Exchange on-premise