The article you linked refers to "local" indexes that reside on a user's computer in the .pst file, etc.. For most exchange driven mail, the messages and indexes reside on the remote server and you may not have a local .pst file which contains your messages, therefore it can't be indexed.. If that's the case here, I suggest contacting the IT folks that maintain the exchange server and see if they have any advice.
Hope this helps.
I have got windows 7-64 bit with outlook 2010 retrieving my work email ( exchange)
Recently I realized when I search outlook sent folder nothing get displayed.
Initially problem was with " Search Tools --> Indexing status ".
I followed the instruction in the ink below :
But still I am having same issue