If my organization is running Exchange Server 2016, do I need a Hybrid Edition key?

No. Exchange Server 2016 includes native hybrid capabilities, so you can connect your Exchange Server 2016 organization to Exchange Online without a Hybrid Edition server. The Hybrid Edition is only for organizations running Exchange Server 2007 or Exchange Server 2010. Exchange Server 2010 customers can also continue to connect their organizations directly to Exchange Online without an additional Hybrid Edition server if they are updated to the latest Service Pack, or can choose to install an Exchange Server 2016 hybrid server. Exchange 2003 customers can continue to use Exchange 2010 Hybrid Edition servers to connect to Exchange Online with the latest Service Pack.

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