Ever wondered what version of Exchange your tenant is provisioned on? Michael Van Horenbeeck has written quick post on how to determine this. I think this will be really handy in the near future so I wanted to share it.
You can check the version by issuing the following cmd via powershell:
Get-OrganizationConfig | ft AdminDisplayVersion,IsUpgradingOrganization
Michael has some great information in his post that can be found here so be sure to check it out.