基于c#发送Outlook邮件（仅SMTP版本）

Yes, I am using SMTP client submission.

This is the c# code:

                var smtpClient = new SmtpClient()
                {
                    Host = "smtp.office365.com",
                    Port = 587,
                    UseDefaultCredentials = false,
                    EnableSsl = true
                };

                smtpClient.Credentials = new NetworkCredential("*** 发送邮箱账号 ***", "密码");

                var message = new MailMessage
                {
                    From = new MailAddress("*** 发送邮箱账号 ***"),
                    Sender = new MailAddress("*** 接收邮箱账号 ***"),
                    Subject = "Test mail",
                    IsBodyHtml = false
                };
                message.To.Add("*** 接收邮箱账号 ***");

                message.Body = "This is a test mail. ";

                smtpClient.Send(message);

            string smtpServer = "smtp.office365.com";
            int smtpPort = 587;
            string mailFrom = "xxx@outlook.com";
            string passWord = "xxxxxx";
            string mailTo = "xxxx@qq.com";
            SmtpClient smtpClient = new SmtpClient(smtpServer, smtpPort);
            smtpClient.UseDefaultCredentials = false;//写到这里不报错
            smtpClient.Credentials = new NetworkCredential(mailFrom, passWord);
            smtpClient.EnableSsl = true;
            //smtpClient.UseDefaultCredentials = false;//写到这里会报错,必须在账号密码绑定前写。
            MailAddress mailAddressFrom = new MailAddress(mailFrom);
            MailAddress mailAddressTo = new MailAddress(mailTo, "xx的QQ邮箱");
            MailMessage mailMessage = new MailMessage(mailAddressFrom, mailAddressTo);
            mailMessage.Subject = "用c#测试发送邮件";
            mailMessage.Body = "这是一次测试发送，发送人用的outlook邮箱";
            mailMessage.BodyEncoding = Encoding.UTF8;
            smtpClient.Send(mailMessage);