public interface IEmailFactory

    {

        IEmailFactory SetHost(string host);

        IEmailFactory SetPort(int port);

        IEmailFactory SetUserName(string userName);

        IEmailFactory SetPassword(string password);

        IEmailFactory SetSSL(bool enableSsl);

        IEmailFactory SetTimeout(int timeout);

        IEmailFactory SetFromAddress(string address);

        IEmailFactory SetFromDisplayName(string displayName);

        IEmailFactory LoadFromConfigFile(); //从Config文件中加载配置

        IEmailFactory SetSubject(string subject);

        IEmailFactory SetBody(string body);

        /// <summary>

        /// 添加收件人地址（执行多次即添加多个地址）

        /// </summary>

        IEmailFactory SetToAddress(params string[] addresses);

        /// <summary>

        /// 添加抄送人地址（执行多次即添加多个地址）

        /// </summary>

        IEmailFactory SetCcAddress(params string[] addresses);

        /// <summary>

        /// 添加附件（执行多次即添加多个附件）

        /// </summary>

        IEmailFactory SetAttachment(params Attachment[] attachments);

        void Send();

        Task SendAsync();

    }

class EmailFactory : IEmailFactory

    {

        #region properties

        protected string Host { get; set; }

        protected int Port { get; set; }

        protected string UserName { get; set; }

        protected string Password { get; set; }

        protected bool EnableSSL { get; set; }

        protected int? Timeout { get; set; }

        protected string FromAddress { get; set; }

        protected string FromDisplayName { get; set; }

        protected string Subject { get; set; }

        protected string Body { get; set; }

        protected IList<string> ToList { get; set; }

        protected IList<string> CcList { get; set; }

        protected IList<Attachment> Attachments { get; set; }

        #endregion

        #region initial methods

        public IEmailFactory SetHost(string host)

        {

            this.Host = host;

            return this;

        }

        public IEmailFactory SetPort(int port)

        {

            this.Port = port;

            return this;

        }

        public IEmailFactory SetSSL(bool enableSsl)

        {

            this.EnableSSL = enableSsl;

            return this;

        }

        public IEmailFactory SetTimeout(int timeout)

        {

            this.Timeout = timeout;

            return this;

        }

        public IEmailFactory SetUserName(string userName)

        {

            this.UserName = userName;

            return this;

        }

        public IEmailFactory SetPassword(string password)

        {

            this.Password = password;

            return this;

        }

        public IEmailFactory SetFromAddress(string address)

        {

            this.FromAddress = address;

            return this;

        }

        public IEmailFactory SetFromDisplayName(string displayName)

        {

            this.FromDisplayName = displayName;

            return this;

        }

        public IEmailFactory LoadFromConfigFile()

        {

            var section = ConfigurationManager.GetSection("system.net/mailSettings/smtp") as System.Net.Configuration.SmtpSection;

            this.Host = section.Network.Host;

            this.Port = section.Network.Port;

            this.EnableSSL = section.Network.EnableSsl;

            this.UserName = section.Network.UserName;

            this.Password = section.Network.Password;

            this.FromAddress = section.From;

            return this;

        }

        public IEmailFactory SetSubject(string subject)

        {

            this.Subject = subject;

            return this;

        }

        public IEmailFactory SetBody(string body)

        {

            this.Body = body;

            return this;

        }

        public IEmailFactory SetToAddress(params string[] addresses)

        {

            if (this.ToList == null) this.ToList = new List<string>();

            if (addresses != null)

                foreach (var item in addresses)

                    this.ToList.Add(item);

            return this;

        }

        public IEmailFactory SetCcAddress(params string[] addresses)

        {

            if (this.CcList == null) this.CcList = new List<string>();

            if (addresses != null)

                foreach (var item in addresses)

                    this.CcList.Add(item);

            return this;

        }

        public IEmailFactory SetAttachment(params Attachment[] attachments)

        {

            if (this.Attachments == null) this.Attachments = new List<Attachment>();

            if (attachments != null)

                foreach (var item in attachments)

                    this.Attachments.Add(item);

            return this;

        }

        #endregion

        public virtual void Send()

        {

            using (SmtpClient smtp = new SmtpClient(this.Host, this.Port))

            {

                var message = PreSend(smtp);

                smtp.Send(message);

            }

        }

        public virtual async Task SendAsync()

        {

            using (SmtpClient smtp = new SmtpClient(this.Host, this.Port))

            {

                var message = PreSend(smtp);

                await smtp.SendMailAsync(message);

            }

        }

        private MailMessage PreSend(SmtpClient smtp)

        {

            if (this.UserName != null && this.Password != null)

            {

                smtp.UseDefaultCredentials = false;

                smtp.DeliveryMethod = SmtpDeliveryMethod.Network;

                smtp.Credentials = new System.Net.NetworkCredential(this.UserName, this.Password);

            }

            if (this.Timeout == null)

                smtp.Timeout = ;

            var message = new MailMessage();

            message.From = new MailAddress(this.FromAddress, this.FromDisplayName, Encoding.UTF8);

            if (this.ToList != null)

                foreach (var address in this.ToList)

                    message.To.Add(address);

            if (this.CcList != null)

                foreach (var address in this.CcList)

                    message.CC.Add(address);

            if (this.Attachments != null)

                foreach (var attachment in this.Attachments)

                    message.Attachments.Add(attachment);

            message.Subject = this.Subject;

            message.SubjectEncoding = Encoding.UTF8;

            message.Body = this.Body;

            message.IsBodyHtml = true;

            message.BodyEncoding = Encoding.UTF8;

            message.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;

            return message;

        }

    }

public class EmailWrapper

    {

        private static readonly EmailHelper _instance = new EmailHelper();

        private EmailHelper() { }

        public static IEmailFactory Initalize

        {

            get { return _instance.GetFactory(); }

        }

        private IEmailFactory GetFactory()

        {

            return new EmailFactory();

        }

    }