Exchange 2016 on Windows Server 2012 R2 Core

I know that Microsoft doesn’t support Exchange 2016 on Windows Server Core or Nano Server. But I decided to find out is it possible or not.

During install Exchange 2016 CU3 on Windows Server 2012 R2 Core (Standard Edition without "Server-Gui-Shell" and "Server-Gui-Mgmt-Infra" features) with checked "Automatically install Windows Server roles and features that are required to install Exchange Server" wizard installs GUI by self.

If you run the installation without "Automatically install Windows Server roles and features that are required to install Exchange Server" wizard returns an error that you need to install "Failover Cluster Management Tools", "IIS 6 Management Console", "IIS Management Console" and "Graphical Management Tools and Infrastructure" features.
So, you can't install Exchange 2016 on Windows Server 2012 R2 Core.

What if disable GUI on installed Exchange Server?

Surprisingly, the Exchange server with GUI allows you run the cmdlet

Remove-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra

Verify. All mailbox databases are mounted and healthy. OWA works.

But, "Test-ServiceHealth" show that 2 Exchange services couldn't start: "Microsoft Exchange Mailbox Assistants" and "Microsoft Exchange Unified Messaging".

What they do?
Microsoft Exchange Mailbox Assistants - "Performs background processing of mailboxes in the Exchange store."
Microsoft Exchange Unified Messaging - "Enables Microsoft Exchange Unified Messaging features. This allows voice and fax messages to be stored in Exchange and gives users telephone access to e-mail, voice mail, calendar, contacts, or an auto attendant."

The difference between Core and GUI

Practically, I found that the install/uninstall GUI affects the following features:

Display Name	Name	GUI	Core
IIS Management Console	Web-Mgmt-Console	Installed	Available
IIS 6 Management Console	Web-Lgcy-Mgmt-Console	Installed	Available
Ink and Handwriting Services	InkAndHandwritingServices	Installed	Available
Failover Cluster Management Tools	RSAT-Clustering-Mgmt	Installed	Available
User Interfaces and Infrastructure	User-Interfaces-Infra	Installed	Available
Graphical Management Tools and Infrastructure	Server-Gui-Mgmt-Infra	Installed	Available
Desktop Experience	Desktop-Experience	Installed	Available
Server Graphical Shell	Server-Gui-Shell	Installed	Available
Windows Identity Foundation 3.5	Windows-Identity-Foundation	Installed	Available
Windows PowerShell ISE	PowerShell-ISE	Installed	Available

Comparison of number of services:

Service State	GUI	Core
Running	97	86
Running (not Exchange)	74	65
Stopped	94	59
Stopped (not Exchange)	88	52

What about Exchange 2016 Edge?

It looks as if all is well. All necessary services are running.

The health report does not show any issues.

Get-HealthReport -Server exchange-edge | where { $_.alertvalue -ne "Healthy" }

Conclusion

You can run Exchange 2016 Mailbox Role on Core and save about 200 MB RAM, but should not do it yet. Edge may well live on Core.