One of our clients has exchange 2010 and one user has a huge mailbox (currently about 65GB) so has to work in non-cached mode rather than cached mode. His OST file just stopped working at 50GB. The user is complaining that searches are not returning all the results it should. Since he is using online mode, I assumed that all the indexing was being done by exchange server and rebuilt the index for the database he was using. (He and one other person share a whole exchange database, the rest of the company is on a different database.) He is still complaining that the search is not returning all the results. I know that when you are in cached mode, the email is indexed by Windows indexing, but what happens in non-cached mode?