I like Exchange Server from 2000 versions. I use Exchange Server in all our customers servers because they do not want external services. But beginning deprecating features with Exchange Server 2013, like EMC, and now with this, there are no reason to continue using Exchange Server. Never use Exchange Online Protection (EOP) because they do not want external services, also never pay for a subcription, only pay one time for a license.
Every day i have less trust in the cloud and more less trust in Microsoft.
I have plans to migrate in this year all Windows Server 2008 R2 with Exchange Server 2010 to Windows Server 2016 and Exchange Server 2016, but without filtering and antispam i cancel the update. Also seeing a lot of telemetry services, 2 xbox live services, Onedrive, Phone, Contacts, Maps, Mobile devices, Geolocation, Camera, Radios (Phone,Airplane mode) and Wallet services installed by default in Windows Server 2016 with no option to uninstall it, is the best reason to stick with Windows Server 2008 R2 and Exchange Server 2010.
Now searching to a good Linux server and a good email server program (not service).