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 = 587;//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);
            }
        }
    }
}