Sending email through SendGrid using the SendGrid Node.js Library that includes an attached image using CID. Does not display correctly with Gmail, Yahoo, or Hotmail (such is the nature of CID).

mailWithAttachedImage.js

var SendGrid = require('sendgrid').SendGrid;

var sendgrid = new SendGrid('username', 'password');
sendgrid.send({
  to: '[email protected]',
  from: '[email protected]',
  fromname: 'Test Person',
  subject: 'Hello World',
  text: 'My first email through SendGrid',
  html: 'My first email with SendGrid with html <img src="cid:testme" alt="graphic"/>',
  files: [
    {
      filename: 'sendgrid_logo-8f6ec9845f58c180692f02f6cb6ec894.png',          // required only if file.content is used.
      url: 'http://sendgrid.com/mkt/assets/sendgrid_logo-8f6ec9845f58c180692f02f6cb6ec894.png',               // == One of these three options is required
      content: ('testme' | Buffer) //
    }
  ],
}, function(success, message) {
  if (!success) {
    console.log(message);
  }
});