public void TestGetRcpts()
        {
            var foo = new Mock<IHeader>();
            var sg = new SendGrid(foo.Object);

            sg.AddTo("*****@*****.**");
            sg.AddCc("*****@*****.**");
            sg.AddBcc("*****@*****.**");
            sg.AddBcc("*****@*****.**");

            var rcpts = sg.GetRecipients();
            Assert.AreEqual("*****@*****.**", rcpts.First(), "getRecipients check To");
            Assert.AreEqual("*****@*****.**", rcpts.Skip(1).First(), "getRecipients check Cc");
            Assert.AreEqual("*****@*****.**", rcpts.Skip(2).First(), "getRecipients check Bcc");
            Assert.AreEqual("*****@*****.**", rcpts.Skip(3).First(), "getRecipients check Bcc x2");
        }