A majority of Notes Mail users will have personal silos of information, most of it corporate, stacked up in their mail file and possibly also contained in several archive databases.
When they want to search that information, they have to know roughly where the target resides, i.e. their production mail or whatever archive, because there is no central index. That means opening each database manually and searching it individually.
Furthermore, the results of a Notes Mail search are quite poor - you get the same row-based information as a Notes View - so if you're searching on a common word, i.e. the name of a major client, you might get hundreds of search results. If all you see is basic summary information (Sender/Recipient, Date, Subject), how do you find the email you want?
The answer is you open each email and scroll through to see if it's the one you want. If you can't find it, you widen your search and start again.
That's horribly inefficient, and means users can take a long time to achieve something as trivial as finding an email.
What Notes has long needed is a multi-database/file system personal search tool (think a Site Search for your mail, archives, local databases and local file system), where the search starts from Notes itself, and the results show you your search phrases in the context of the document. You can then perform only one search, scan documents from the result set via document-context information, and quickly find the target email.
As an example, if you were searching for an email you received last year, which mentioned something about a major client 'ACME' starting a project, you might search using a query like 'ACME and Project'. Using the result set, you'd then have to guess from the brief summary information provided which document it might be, and open each one to check the contents.
However if the result set showed the search query in the context of each document, then it's pretty simple to identify the email you want.
This is exactly what we've done with the FT Search Manager, and it makes finding information in mail (no matter it's location) much, much faster. Until IBM provide better search tools in Notes, solutions like this can save you a lot of time, and therefore money.