Outlook - Smart search
Outlook 2011 for Mac can do that: just skip the space. So, from:John. 

It shows your smart search options as you type. Click one of these (or just type them with the colon), and it'll search only that type of thing:





Or, you can click in the quick search box, then click the "From" button in the "search" ribbon section that appears...



...then type "John" in the different box that appears.

Less typing, but one extra click.