This is a trivial cn1lib for sending emails using sendgrid. It doesn't support most of the features of sendgrid but can support everything if we want to add it. It's trivial and based on the REST API.
SendGrid s = SendGrid.create(YOUR_SEND_GRID_API_TOKEN); s.sendSync(toEmail, fromEmail, subject, body);
Notice you will need a sendgrid account which is available for free with 100 free emails per day. The signup wizard provides a button to generate the API token.