Microsoft has released a Windows Desktop Search Add-in for Lotus Notes

Once you have installed this Add-in, Windows Desktop Search (WDS) will index the content of your locally stored Lotus Notes databases. Indexing will occur when your PC is idle, or when you tell WDS to Index Now. Once the index is updated you can immediately search your Lotus Notes content.

Note: Please uninstall any previous versions of the Add-in for Lotus Notes before installing this updated version. After you install this Add-in, please ensure you select the databases that you want included via the Windows Desktop Search preferences screens.

Windows Desktop Search: Add-in for Lotus Notes