var postage = require('postage')('YOUR API KEY');

var options = { 
  recipients: 'email@address.com',
  subject: 'Subject Line',
  from: 'sender@example.org',
  content: {
    'text/html': '<p>Some awesome content</p>',
    'text/plain': 'Plain text goes here (if any)'
  }
};

postage.send(options, function callback(error, msg) {
  if (error) {
    console.error(error);
  } else {
    console.log(message);
  }
});