Last week, Gmail rolled out two new features, “Don't forget Bob” and “Got the wrong Bob?”, Which have been developed at Gmail Labs since April and October 2009, respectively. The first one suggests a “forgotten” email recipient with several recipients. The second function corrects the recipient's address so that you do not accidentally send a letter to an erroneous recipient with a similar name.
Obviously, for everything to work as it should, the system must analyze your personal correspondence. This is how the first function works.