There are a few different binaries that make up the Enterprise Vault Outlook Add-in. Some you might have heard of, and some you might not. The most 'famous' of all is Valkyrie.dll. A new-kid on the block is EVMSP.dll, but what is it?
Here is a screenshot of EVMSP32.DLL on one of my Windows 8 test systems
If you use Outlook and launch Process Explorer you will most likely see that EVMSP32.dll has been loaded by Outlook. The file is part of the glue that forms the Virtual Vault function within the Outlook Add-in.