一个关于发邮件的类，可以模拟发送对smtp服务器或者是本地文件夹

 namespace SportsStore.Domain.Concrete {

     public class EmailSettings {
         public string MailToAddress = "orders@example.com";
         public string MailFromAddress = "sportsstore@example.com";
         public bool UseSsl = true;
         public string Username = "MySmtpUsername";//MailToAddress一样
         public string Password = "MySmtpPassword";
         public string ServerName = "smtp.example.com";
         public int ServerPort = ;//Gmail为587,其他一般为25
         public bool WriteAsFile = false;//设为false邮件将发送到路径FileLoacation
         public string FileLocation = @"c:\sports_store_emails";
     }

     public class EmailOrderProcessor :IOrderProcessor {
         private EmailSettings emailSettings;

         public EmailOrderProcessor(EmailSettings settings) {
             emailSettings = settings;
         }

         public void ProcessOrder(Cart cart, ShippingDetails shippingInfo) {

             using (var smtpClient = new SmtpClient()) {

                 smtpClient.EnableSsl = emailSettings.UseSsl;
                 smtpClient.Host = emailSettings.ServerName;
                 smtpClient.Port = emailSettings.ServerPort;
                 smtpClient.UseDefaultCredentials = false;
                 smtpClient.Credentials
                     = new NetworkCredential(emailSettings.Username, emailSettings.Password);
                 if (emailSettings.WriteAsFile) {
                     smtpClient.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory;
                     smtpClient.PickupDirectoryLocation = emailSettings.FileLocation;
                     smtpClient.EnableSsl = false;
                 }

                 StringBuilder body = new StringBuilder()
                 .AppendLine("A new order has been submitted")
                 .AppendLine("---")
                 .AppendLine("Items:");

                 foreach (var line in cart.Lines) {
                     var subtotal = line.Product.Price * line.Quantity;
                     body.AppendFormat("{0} x {1} (subtotal: {2:c}", line.Quantity,
                                       line.Product.Name,
                                       subtotal);
                 }
                 body.AppendFormat("Total order value: {0:c}", cart.ComputeTotalValue())
                 .AppendLine("---")
                 .AppendLine("Ship to:")
                 .AppendLine(shippingInfo.Name)
                 .AppendLine(shippingInfo.Line1)
                 .AppendLine(shippingInfo.Line2 ?? "")
                 .AppendLine(shippingInfo.Line3 ?? "")
                 .AppendLine(shippingInfo.City)
                 .AppendLine(shippingInfo.State ?? "")
                 .AppendLine(shippingInfo.Country)
                 .AppendLine(shippingInfo.Zip)
                 .AppendLine("---")
                 .AppendFormat("Gift wrap: {0}", shippingInfo.GiftWrap ? "Yes" : "No");

                 MailMessage mailMessage = new MailMessage(
                                        emailSettings.MailFromAddress,   // From
                                        emailSettings.MailToAddress,     // To
                                        "New order submitted!",          // Subject
                                        body.ToString());                // Body

                 if (emailSettings.WriteAsFile) {
                     mailMessage.BodyEncoding = Encoding.ASCII;
                 }

                 smtpClient.Send(mailMessage);
             }
         }
     }
 }