MailSmtp ms = new MailSmtp("smtp.qq.com","1215247044","xxxx");
     //可选参数
     ms.SetCC("610262374@qq.com");//抄送可以多个
     ms.SetBC("610262374@qq.com");//暗送可以多个
     ms.SetIsHtml(true);//默认:true
     ms.SetEncoding(System.Text.Encoding.UTF8);//设置格式 默认utf-8
     ms.SetIsSSL(true);//是否ssl加密 默认为false
     //调用函数
     bool isSuccess = ms.Send("1215247044@qq.com", "test", "610262374@qq.com", "哈哈", "哈哈", Server.MapPath("~/Test.dll"));
     //输出结果
     Response.Write(ms.Result); 
　　

using System;
using System.IO;
using System.Web.UI.WebControls;
using System.Text;
using System.Net.Mail;
using System.Net;
using System.Linq;
using System.Text.RegularExpressions;
namespace SyntacticSugar
{
  /// <summary>
  /// ** 描述：邮件发送
  /// ** 创始时间：2015-6-8
  /// ** 修改时间：-
  /// ** 作者：sunkaixuan
  /// </summary>
  public class MailSmtp
  {
    /// <summary>
    /// 设置邮件编码类型
    /// </summary>
    /// <param name="contentEncoding"></param>
    public void SetEncoding(Encoding contentEncoding)
    {
      this._encoding = contentEncoding;
    }
    /// <summary>
    ///设置邮件正文是否为 Html 格式 
    /// </summary>
    /// <param name="isHtml"></param>
    public void SetIsHtml(bool isHtml)
    {
      this._isHtml = isHtml;
    }
    /// <summary>
    /// 抄送
    /// </summary>
    /// <param name="cc"></param>
    public void SetCC(params string[] cc)
    {
      this._cc = cc;
    }
    /// <summary>
    /// 暗送
    /// </summary>
    /// <param name="cc"></param>
    public void SetBC(params string[] bc)
    {
      this._bcc = bc;
    }
    /// <summary>
    /// 是否ssl加密
    /// </summary>
    /// <param name="isSSL"></param>
    public void SetIsSSL(bool isSSL)
    {
      this._smtp.EnableSsl = isSSL;
    }
    /// <summary>
    /// 构造函数
    /// </summary>
    /// <param name="host"></param>
    /// <param name="username">邮件账号</param>
    /// <param name="password">密码</param>
    public MailSmtp(string host, string username, string password)
    {
      this._smtp.Host = host;
      this._smtp.Port = 0x19;
      this._smtp.EnableSsl = false;
      this._isHtml = true;
      this._encoding = Encoding.UTF8;
      if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
      {
        this._smtp.UseDefaultCredentials = false;
      }
      else
      {
        this._smtp.Credentials = new NetworkCredential(username, password);
      }
    }
    /// <summary>
    /// 发送邮件
    /// </summary>
    /// <param name="from">发件人邮件地址</param>
    /// <param name="sender">发件人显示名称</param>
    /// <param name="to">收件人地址</param>
    /// <param name="subject">邮件标题</param>
    /// <param name="body">邮件正文</param>
    /// <param name="file">附件地址数组</param>
    /// <returns>bool 是否成功 </returns>
    public bool Send(string from, string sender, string to, string subject, string body, params string[] file)
    {
      return Send(from, sender, new string[] { to }, subject, body, file);
    }
    /// <summary>
    /// 发送邮件
    /// </summary>
    /// <param name="from">发件人邮件地址</param>
    /// <param name="sender">发件人显示名称</param>
    /// <param name="to">收件人地址</param>
    /// <param name="subject">邮件标题</param>
    /// <param name="body">邮件正文</param>
    /// <param name="file">附件地址数组</param>
    /// <returns>bool 是否成功 </returns>
    public bool Send(string from, string sender, string[] to, string subject, string body, params string[] file)
    {
      string mailReg = @"^[\w-]+(\.[\w-]+)*@[\w-]+(\.[\w-]+)+$";
      if (to == null)
      {
        throw new ArgumentNullException("MailSmtp.Send.to");
      }
      if (to.Any(oit => !Regex.IsMatch(oit + "", mailReg)))
      {
        this.Result = "收件人地址不合法";
        return false;
      }
      if (_bcc != null && _bcc.Length > 0)
      {
        if (_bcc.Any(oit => !Regex.IsMatch(oit + "", mailReg)))
        {
          this.Result = "暗送人地址不合法";
          return false;
        }
      }
      if (_cc != null && _cc.Length > 0)
      {
        if (_cc.Any(oit => !Regex.IsMatch(oit + "", mailReg)))
        {
          this.Result = "抄送人地址不合法";
          return false;
        }
      }
      MailMessage message = new MailMessage();
      // 创建一个附件对象
      foreach (var r in file)
      {
        Attachment objMailAttachment;
        objMailAttachment = new Attachment(r);//发送邮件的附件
        message.Attachments.Add(objMailAttachment);
      }
      message.From = new MailAddress(from, sender);
      message.Subject = subject;
      message.SubjectEncoding = this._encoding;
      message.Body = body;
      message.BodyEncoding = this._encoding;
      message.IsBodyHtml = this._isHtml;
      message.Priority = MailPriority.Normal;
      foreach (string str in to)
      {
        message.To.Add(str);
      }
      if (this._bcc != null && this._bcc.Length > 0)
      {
        foreach (string b in this._bcc)
        {
          message.Bcc.Add(b);
        }
      }
      if (this._cc != null && this._cc.Length > 0)
      {
        foreach (string c in this._cc)
        {
          message.CC.Add(c);
        }
      }
      try
      {
        this._smtp.Send(message);
        return true;
      }
      catch (Exception ex)
      {
        Console.WriteLine(ex.Message);
      }
      return false;
    }
    private SmtpClient _smtp = new SmtpClient();
    private Encoding _encoding { get; set; }
    private bool _isHtml { get; set; }
    private string[] _cc { get; set; }
    private string[] _bcc { get; set; }
    /// <summary>
    /// 获取发送结果，成功则为空
    /// </summary>
    public string Result { get; private set; }
  }
 
}