Spotlight should show email attachments, but note that Spotlight doesn't search system files such as files contained in the Library by default. To do that, do a Command-F in the Finder and then select the Kind pop-up and select "Other..."
There you can find System files and check to add it to the menu so it can be used as one of your search options to find files such as files containd
^ This.
And
saving searches is a good way to speed things up for frequently used patterns.
