Send an email with categories using sendgrid-csharp

gistfile1.cs

// Create the email object first, then add the properties.
SendGrid myMessage = SendGrid.GetInstance();
myMessage.AddTo("anna@example.com");
myMessage.From = new MailAddress("john@example.com", "John Smith");
myMessage.Subject = "Testing the SendGrid Library";
myMessage.Text = "Hello World!";

string[] categories = new string[3] {"category1", "category2", "category3"};

myMessage.SetCategories(categories);

// Create credentials, specifying your user name and password.
var credentials = new NetworkCredential("username", "password");

// Create an SMTP transport for sending email.
var transportSMTP = SMTP.GetInstance(credentials);

// Send the email.
transportSMTP.Deliver(myMessage);