Disabling MAPI over HTTP for Outlook on Enterprise Vault servers

Description

MAPI over HTTP was introduced with Exchange server 2013 SP1 for Outlook 2010 SP1 (with updates KB2956191 and KB2965295) and Outlook 2013 SP1 or later. For more information on MAPI over HTTP, refer to Microsoft MAPI over HTTP.

Enterprise Vault (EV) does not support the use of MAPI over HTTP connections from Outlook 2013 SP1 on the EV server. For this reason, you must disable MAPI over HTTP connections by setting a Registry value on each EV server.

Solution

1. Log on to the EV server as the Vault Service Account (VSA). If you run Exchange archiving tasks under a service account other than the VSA, log on to this other account.
2. Create a registry DWORD value called MapiHttpDisabled under the following Registry key:
   HKEY_CURRENT_USER\Software\Microsoft\Exchange
   Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly.  Great care should be taken when making changes to a Windows registry.  Registry modifications should only be carried-out by persons experienced in the use of the registry editor application.  It is also recommended that a complete backup of the registry and workstation / server be made prior to making any registry changes. 
3. Assign MapiHttpDisabled a value of 1.
4. Restart Outlook on the EV server.

For more information, see the following article: http://blogs.technet.com/b/exchange/archive/2014/05/09/outlook-connectivity-with-mapi-over-http.aspx

Note that Outlook 2016 on Enterprise Vault server supports MAPI over HTTP connection in Enterprise Vault 12.2 or later.