C# 4.0 如何在没有smtp的情况下从exchange server发送邮件？

我目前正在使用smtp从我的代码发送邮件，但似乎我们必须迁移到exchange server，两者之间有区别吗？ 我需要在代码中做哪些更改

MailMessage loginInfo = new MailMessage();
loginInfo.To.Add("estinationaddress.@ca");
loginInfo.From = new MailAddress("abc@sde.ca");
loginInfo.Subject = "ABC";
loginInfo.Body = "Your username is: " +"abc";
loginInfo.IsBodyHtml = true;

SmtpClient smtp = new SmtpClient();
smtp.Host = "www.smtphost.com";
smtp.Port = 25;
smtp.EnableSsl = false;
smtp.Credentials = new System.Net.NetworkCredential("abc@sde.ca","abc");
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Send(loginInfo);

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我需要对代码进行哪些更改？

Exchange是SMTPserver@Barmar：这是我的客户的要求，他们现在要求我使用exchange服务器，所以我很困惑：（SMTP是一种协议，Exchange是实现该协议的软件应用程序。

MailMessage loginInfo = new MailMessage();
loginInfo.To.Add("estinationaddress.@ca");
loginInfo.From = new MailAddress("abc@sde.ca");
loginInfo.Subject = "ABC";
loginInfo.Body = "Your username is: " +"abc";
loginInfo.IsBodyHtml = true;

SmtpClient smtp = new SmtpClient();
smtp.Host = "www.smtphost.com";
smtp.Port = 25;
smtp.EnableSsl = false;
smtp.Credentials = new System.Net.NetworkCredential("abc@sde.ca","abc");
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Send(loginInfo);