A friend  of mine mentioned Lookout . An indexing search engine working as plug-in for Microsoft Outlook. The company has recently been bought by Microsoft. So the license agreement looks a bit strange to me (here just the beginning):
License, Limited Warranty and Copyright
IMPORTANT-READ CAREFULLY: This is a legal agreement between you (either an individual or a single entity) and Microsoft Corporation (The Company) for Lookout (The Software). If you do not agree to all of the terms of this License, then do not use, copy or install The Software.
This Software is protected by copyright laws and international treaty provisions. All rights reserved. Please read the license terms below. Portions of this software are Copyright (c) 2001 The Apache Software Foundation. All rights reserved. Please read the Apache Software License included in this document. For more information on the Apache Software Foundation, please see http://www.apache.org. […]
This seems like the first Microsoft software licensed under an Apach license.