heroku - set up SendGrid on Rails app -

I am using sendgrid and action mailer to send emails from my rail app that has been deployed in Heroku. My emails are being delivered but I do not see any email activity in Sendgrid Open Tracking App is enabled

I was thinking that I have set up the app correctly? I am using sendgrid-ruby gem and I have set

  config.action_mailer.default_url_options = {host: ENV ["DOMAIN"]}  

< P> and

activator :: base. Smtp_settings = {: address = & gt; 'Smtp.sendgrid.net' ,: port = & gt; '587',: Authentication = & gt; : Plain ,: user_name = & gt; ENV ['SENDGRID_USERNAME'] ,: Password = & gt; ENV ['SENDGRID_PASSWORD'],: domain = & gt; 'Heroku.com' ,: enable_starttls_auto = & gt; Correct}

Do I need to do something else?