If you have chosen one of the two following options in your List Settings:
i) Activate Double Opt-in for this list but continue sending to all subscribers
ii) Activate Double Opt-in for this list and only send to verified subscribers
Then, when you select the View list, you will notice that a new column has appeared named: Double opt-in and the email address has the status Verified.
That means that this specific user has given you the consent via the Double Opt-in mechanism to send him Email Marketing newsletters.