异步邮件发送

using System;
using System.Net.Mail;
using System.Collections.Specialized;

namespace MS.Core.Common
{
    public sealed class SMTPEmailer
    {
        #region 私有常量

        private static string _fromAddress = "Jay.Sky001@163.com";
        private static string _fromAlias = "Mr Vis";
        private static string _toAlias = "Dear Friends";
        private static string _toAddress = "MyMuse@foxmail.com";
        private static string _ccAddress = "";//抄送
        private static string _bccAddress = "";//密送

        private static string _smtpServer = "smtp.163.com";
        private static bool _isEmailEnabled = true;

        #endregion 

        #region 私有变量

        private static MailMessage message;

        #endregion

        #region 公有方法

        static SMTPEmailer()
        {
        }

        /// <summary>
        /// 邮件发送重载方法
        /// </summary>
        /// <param name="subject"></param>
        /// <param name="body"></param>
        public static void SendEmail(string subject, string body)
        {
            if (_isEmailEnabled)
            {
                CreateMessage(subject, body);
                SendMail();
            }
        }

        /// <summary>
        /// 邮件发送重载方法
        /// </summary>
        /// <param name="subject"></param>
        /// <param name="body"></param>
        /// <param name="attachment"></param>
        public static void SendEmail(string subject, string body, string attachment)
        {
            if (_isEmailEnabled)
            {
                CreateMessage(subject, body);

                if (!string.IsNullOrEmpty(attachment))
                {
                    if (System.IO.File.Exists(attachment))
                        message.Attachments.Add(new Attachment(attachment));
                    else
                        throw new Exception(string.Format("Attachment {0} not found", attachment));
                }

                SendMail();
            }
        }


        /// <summary>
        /// 邮件发送重载方法
        /// </summary>
        /// <param name="fromAddress"></param>
        /// <param name="fromAlias"></param>
        /// <param name="toAddress"></param>
        /// <param name="ccAddress"></param>
        /// <param name="bccAddress"></param>
        /// <param name="subject"></param>
        /// <param name="body"></param>
        /// <param name="attachment"></param>
        public static void SendEmail(string fromAddress, string fromAlias, string toAddress,
            string ccAddress, string bccAddress, string subject, string body, string attachment)
        {
            if (_isEmailEnabled)
            {
                _fromAddress = fromAddress;
                _fromAlias = fromAlias;
                _toAddress = toAddress;
                _ccAddress = ccAddress;
                _bccAddress = bccAddress;

                CreateMessage(subject, body);

                if (!string.IsNullOrEmpty(attachment))
                {
                    if (System.IO.File.Exists(attachment))
                        message.Attachments.Add(new Attachment(attachment));
                    else
                        throw new Exception(string.Format("Attachment {0} not found", attachment));
                }

                SendMail();
            }
        }

        #endregion

        #region 私有方法

        /// <summary>
        /// 创建邮件信息
        /// </summary>
        /// <param name="subject"></param>
        /// <param name="body"></param>
        private static void CreateMessage(string subject, string body)
        {
            if (message == null)
            {
                message = new MailMessage();
                message.From = new MailAddress(_fromAddress, _fromAlias);
                message.Subject = subject;
                message.Body = body;
                //message.To.Add(_toAddress);
                message.To.Add(new MailAddress(_toAddress, _toAlias));
                if (!string.IsNullOrEmpty(_ccAddress))
                    message.CC.Add(_ccAddress);
                if (!string.IsNullOrEmpty(_bccAddress))
                    message.Bcc.Add(_bccAddress);
            }
        }

        /// <summary>
        /// 发送邮件
        /// </summary>
        private static void SendMail()
        {
            SmtpClient client = new SmtpClient(_smtpServer);
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            client.Credentials = new System.Net.NetworkCredential("邮箱账号", "邮箱密码");
            client.SendCompleted += new SendCompletedEventHandler(client_SendCompleted);
            client.SendAsync(message, "发送中..");
            message = null;
        }

        /// <summary>
        /// 邮件发送之后的异步操作
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private static void client_SendCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
        {
            // 获取此异步操作的独特标识符
            String token = (string)e.UserState;

            if (e.Error != null)
            {
                throw e.Error;
            }
            else
            {
                //成功后操作
            }
        }

        #endregion 
    }
}