Google (NASDAQ:GOOG) has added a new feature to its search engine: the ability to also look through users’ private Gmail account for anything related to the search request. For example, searching “Amazon” (NASDAQ:AMZN) could bring up e-mails related to shipping orders, or searching “flight” could bring up a travel itinerary, The Associated Press reports.

Here are five things to know about the new search engine:

• Google is, at this point, still only testing the feature. It will initially be available to 1 million Gmail users who sign up at http://g.co/searchtrial.
• The mail search results will be shown to the right of the main results or at the top of the search page.
• Google hopes to give all Gmail users the option of plugging their accounts into the main search engine after the test is finished and feedback is received.
• The  company did say that it is willing to display information from other email services down the road.
• Google’s ultimate goal is to personalize the search engine experience so much that it can answer users’ questions to a point not previously thought possible.