Ever since the 3rd party “Lookout” add-in was built for Outlook about 8 years ago, the pilers have inherited the earth. That’s pilers. No connection with Chaka Demus.
Research as far back as the early 1980s into how people organise their desks suggested there were “filers” – meticulously organised people who have a place for everything and put everything in its place, or “pilers” who just let it all build up.
Actually, it’s more complicated than that – pilers have “hot”, “warm” and “cool” areas of their desk defined by the level of activity, so stuff they were working on was commonly nearby. Filers on the other hand, might inadvertently squirrel stuff away and forget all about it. Common belief might be that outwardly more “organised” people are more effective, but the research shows this isn’t necessarily the case. Read more here.
Lookout introduced the ability to just search across your whole mailbox, in literally an instant – doesn’t sound all that special today but in 2004, it was absolutely revolutionary. Imagine searching your whole mailbox (all 200Mb of it, wow!! – though some companies gave their users bigger mailboxes) in the blink of an eye… No longer did you need to file anything, or remember the subject line, or the date it was sent – recall any attribute of the message and you can always find it later.
As it turns out, Microsoft bought the company and then incorporated similar technology into Outlook and Windows directly. The main man in LookoutSoft left MS after his career peak and a couple of 
years, to go and work at a grubby advertising company. Never mind.
Anyway, back to the present day. Outlook gives the user the option of searching within folder (press CTRL-E to jump straight in and type a search query, then press CTRL-ALT-A to expand the search to all folders if required).
The Ribbon changes when activating the search box to show a bunch of criteria that can be searched upon, with a click:
There are, however, a few other options… mostly to do with the way one expresses a query in the search box. Just type in a word and your query will return any item which contains that word, however if you put subject: search word or subject: “search phrase”, then you can restrict the search results to only key words from the subject line.
Similarly, from:”joe blogs” or from:”joe bloggs” subject: “blah blah” will restrict ever further to just mail from an individual or even specific mail from that person with certain words in the subject.
There are some other esoteric search terms, too. Running out of mailbox space? Try messagesize:>5mb and you’ll see only the huge emails. Or for the same filter, simply add messagesize:enormous.
Many more examples of search criteria can be found here.
