The following table shows examples of searches you might find useful. The search query syntax, available when the Instant Search feature is enabled, follows this basic form: keyword:your search criteria value.

For example, from:bobby

You can also use logical operators AND, NOT, OR, <, >, =, and so forth to refine your search, and these are noted in the table. Logical operators must be typed in uppercase letters.

E THIS TO FIND THIS
bobby Items containing bobby, BOBBY, BoBby, or any other combination of uppercase and lowercase letters. Instant Search is not case sensitive.
bobby moore Items containing both bobby and moore, but not necessarily in that order.
bobby AND moore Items containing both bobby and moore, but not necessarily in that order. Note that logical operators such as AND, NOT, and OR must be in uppercase letters.
bobby NOT moore Items containing bobby, but not moore.
bobby OR moore Items containing bobby, moore, or both.
“bobby moore” Items containing the exact phrase bobby moore. Note the use of double quotes so that the search results match the exact phrase within the quotes.
from:”bobby moore” Items sent from bobby moore. Note the use of double quotes so that the search results match the exact phrase within the quotes.
from:”bobby moore” about:”status report” Items sent from bobby moore where status report appears in the subject line, body, and attachment contents. Note the use of double quotes so that the search results match the exact phrase within the quotes.
hasattachment:yes Items that have attachments. You can also use hasattachment:true to get the same results.
attachments:presentation.pptx Items that have attachments named presentation.pptx or if the attachment contains presentation.pptx within its contents.
subject:”bobby moore” Items whose subject contains the phrase bobby moore.
subject:bobby moore Items with bobby in the subject line and with moore anywhere else in the document.
cc:”bobby more” Items in which the display name bobby moore is on the Cc line.
cc:bobbymoore@contoso.com Items in which the e-mail address bobbymoore@contoso.com is on the Cc line.
bcc:bobby Items in which bobby is on the Bcc line.

Sources: http://office.microsoft.com/en-in/outlook-help/learn-to-narrow-your-search-criteria-for-better-searches-in-outlook-HA010238831.aspx