将图像添加到未显示的电子邮件中

Question

我正在尝试将图像添加到ASP.NET MVC中的电子邮件中，我得到以下代码，它确实发送了电子邮件，但图像最初没有出现，我必须打开电子邮件，关闭它并打开它再一次，我做错了什么？

var message += "<img src='https://chart.googleapis.com/chart?chs=250x250&cht=qr&chl=abc%20123%20456&choe=UTF-8' />";

            using (SmtpClient client = new SmtpClient("xxx.xxx.x.xx"))
            {
                MailAddress to = new MailAddress("john@example.com");
                MailAddress from = new MailAddress("email@example.com");
                MailMessage email = new MailMessage(from, to);
                email.Subject = "Subject";
                email.Body = message;
                email.IsBodyHtml = true;
                try
                {
                    client.Send(email);
                }
                catch (Exception ex)
                {
                    Console.Write(ex);
                }
            }