One of the many new features delivered in Exchange 2013 SP1 and Exchange 2016 is a new method of connectivity to Outlook referred to as MAPI/HTTP. This protocol was first delivered with the update to Exchange 2013 called SP1 (otherwise known as CU4 or 15.0.847.32), however it needed to be manually enabled. It was also rolled out to Office 365 in May of 2015.
Before we jump into the Exchange Server 2016 configuration, let’s take a look at the requirements:
- Currently the ONLY Outlook clients that support this are:
- Outlook 2016
- Outlook 2013 SP1
- Outlook 2010 (with the January 2015 Update, there were also additional patches released in the April 2015 updates)
- A namespace that your Exchange Organization will use for the MAPI/HTTP connections (This can be the same as your existing namespace)
- Certificates to support the namespace (if you are not using the current namespace)
- Firewall / Load Balancer / Reverse Proxy – these will need to be updated to include the new MAPI virtual directory
- If you are in coexistence with an Exchange 2010 Mailbox Server, the behavior will be:
- Exchange 2010 users will use the RPC/HTTP connections to Outlook
- Exchange 2016 users will use only MAPI/HTTP connections to Outlook
First, let’s take a look at the new virtual directory settings. You can use PowerShell to do this with the following command:
Get-MapiVirtualDirectory -server grayex1 | fl
Set-MapiVirtualDirectory -server grayex1 -InternalUrl https://mapi.greyt3ch.com/mapi -ExternalUrl https://mapi.greyt3ch.com/mapi -IISAuthenticationMethods NTLM,Negotiate,OAuth
You will also notice that the virtual directory is visible though IIS also:
There is one more place where MAPI/HTTP can be controlled. With Exchange 2013 this is defaulted to $false and with Exchange 2016 this is defaulted to $true.
Get-OrganizationConfig | fl mapi*
Once everything is configured, be sure to check that it is working. You can do this by looking at the “Connection Status” screen in Outlook:
All the connections going to the server are now using the protocol HTTP.
If you are in coexistence and have an Outlook 2013 SP1 user that needs to connect to an Exchange 2010 mailbox and your CAS frontend is Exchange 2016, you can disable MAPI/HTTP by setting the following registry entry on that workstation:
- Create a new DWORD value named MapiHttpDisabled and set the value to 1