Microsoft Outlook search functionality relies on the Search service for the Instant Search feature. With Outlook 2010/2013 there is more integration available with the Search application. As a result, the SearchIndexer.exe process on an RDS server may cause high CPU and I/O usage as more users log onto the server.

On RDS servers we need the Windows Search Service, which is part of the File Services role in Windows Server 2008 R2 or a Feature in Windows Server 2012.

The Windows Search Pre-Installation Considerations article from Microsoft TechNet mentions that it is supported for Terminal Services, but performance may be affected.

We have been successful bringing the SearchIndexer.exe process under control for RDS use, although we had to disable almost all of the indexing via GPO. However, the search buttons in Outlook 2010 still work.

Recommended GPO Settings

These GPO settings can be updated to turn down the indexing while allowing the Outlook’s instant search feature to function.

  • Windows Components/Search
  • Allow indexing of encrypted files, Disabled
  • Prevent adding UNC locations to index from Control Panel, Enabled
  • Prevent adding user-specified locations to the All Locations menu, Enabled
  • Prevent automatically adding shared folders to the index, Enabled
  • Prevent indexing e-mail attachments, Enabled
  • Prevent indexing of certain file types, Enabled
  • Prevent indexing public folders, Enabled
  • Enable Throttling for online mail indexing, 6 items per minute (maximum is 120 per minute)
  • Prevent indexing certain paths:
    • file:///C:\*
    • outlookexpress://{*}/*
    • otfs://{*}/*
    • mapi://{*}/*
    • mapi15://{*}/*
    • ONEINDEX15://{*}/*
    • iehistory://{*}/

Note: On TS/RDS servers we disable Outlook cache mode. The Exchange Search service on the Exchange Service is required for full-text searches by users using Outlook in online mode

Ultimately, adding the MAPI path exclusions showed the most improvement. In the GPO there is an option to disable Outlook indexing, but that also disables all search options.

Have more questions?

If you have more questions about how to tune the Search feature in Outlook, you can reach our Technology Infrastructure experts at info@peters.com or 630.832.0075.