How to enable or disable MAPI over HTTP in your Exchange 2016 organization.

Source : https://technet.microsoft.com/en-us/library/mt634322(v=exchg.160).aspx

Summary: 

In Exchange 2016, MAPI over HTTP can be set at the organization level or at the individual mailbox level. Mailbox-level settings always take precedence over organization-wide settings.

MAPI over HTTP is enabled by default in new Exchange 2016 topologies

Note:
When MAPI over HTTP is enabled at the organization level, the MapiHttpEnabled parameter of the Get-OrganizationalConfig cmdlet is set to True.

Configure MAPI over HTTP

Make sure you have already configured the prerequisites described inMAPI over HTTP in Exchange 2016.
Virtual directory configuration

Set-MapiVirtualDirectory -Identity "Contoso\mapi (Default Web Site)" -InternalUrl https://Contoso.com/mapi -IISAuthenticationMethods Negotiate

Certificate configuration

The digital certificate used by your Exchange environment must include the same InternalURL and ExternalURL values that are defined on the MAPI virtual directory.

Update server rules   

Verify that your load balancers, reverse proxies, and firewalls are configured to allow access to the MAPI over HTTP virtual directory.

Enable MAPI over HTTP in your Exchange organization

After running the commands below, Outlook clients with MAPI over HTTP enabled will see a message to restart Outlook to use MAPI over HTTP.

Set-OrganizationConfig -MapiHttpEnabled $true

Enable MAPI over HTTP for an individual mailbox

Set-CasMailbox <user or mailbox ID> -MapiHttpEnabled $true
Test MAPI over HTTP connections

The following example tests the MAPI over HTTP connection from the Exchange server named ContosoMail.










Test-OutlookConnectivity -RunFromServerId ContosoMail -ProbeIdentity OutlookMapiHttpSelfTestProbe
A successful test returns output that's similar to the following example:

MonitorIdentity                                          StartTime              EndTime                Result      Error     Exception
---------------                                          ---------              -------                ------      -----     ---------
OutlookMapiHttp.Protocol\OutlookMapiHttpSelfTestProbe    2/14/2016 7:15:00 AM   2/14/2016 7:15:10 AM   Succeeded