null, // OR 'protocol' => 'smtp', // or ses+smtp, gmail+smtp, mandrill+smtp, mailgun+smtp, mailjet+smtp, postmark+smtp, sendgrid+smtp, sendinblue+smtp, ohmysmtp+smtp //we use "username" also as ID, KEY, API_TOKEN, ACCESS_KEY 'username' => 'merchant@yourdomain.com', 'password' => '****super-secret-password****', 'host' => 'your-hostname', 'port' => 465 //or 587 etc ]; */