#region 发送指定邮箱publicstaticstring SendMail(stringfrom, string fromname, string to, string subject, string body, string username, string password, string server, string fujian)
    {
        try
        {
            //邮件发送类            MailMessage mail =new MailMessage();
            //是谁发送的邮件            mail.From =new MailAddress(from, fromname);
            //发送给谁            mail.To.Add(to);
            //标题            mail.Subject = subject;
            //内容编码            mail.BodyEncoding = Encoding.Default;
            //发送优先级            mail.Priority = MailPriority.High;
            //邮件内容            mail.Body = body;
            //是否HTML形式发送            mail.IsBodyHtml =true;
            //附件if (fujian.Length >0)
            {
                mail.Attachments.Add(new Attachment(fujian));
            }
            //邮件服务器和端口            SmtpClient smtp =new SmtpClient(server, 25);
            smtp.UseDefaultCredentials =true;
            //指定发送方式            smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
            //指定登录名和密码            smtp.Credentials =new System.Net.NetworkCredential(username, password);

            //mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1"); //basic authentication 
            //mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", username); //set your username here 
            //mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", password); //set your password here

            //超时时间            smtp.EnableSsl =false;
            smtp.Timeout =10000;
            smtp.Send(mail);
            return"成功发送请注意查收";
        }
        catch (Exception exp)
        {
            return exp.Message;
        }
    }
 ///<summary>///   发送邮件
    ///</summary>///<param   name= "server "> smtp地址 </param>///<param   name= "username "> 用户名 </param>///<param   name= "password "> 密码 </param>///<param   name= "from "> 发信人地址 </param>///<param   name= "to "> 收信人地址 </param>///<param   name= "subject "> 邮件标题 </param>///<param   name= "body "> 邮件正文 </param>///<param   name= "IsHtml "> 是否是HTML格式的邮件 </param>publicstaticstring SendMail(stringfrom, string to, string subject, string body, string server, string username, string password, bool IsHtml)
    {
        try
        {
            //设置SMTP 验证,端口默认为25，如果需要其他请修改            SmtpClient mailClient =new SmtpClient(server, 25);


            //指定如何发送电子邮件。
            //Network   电子邮件通过网络发送到   SMTP   服务器。    
            //PickupDirectoryFromIis   将电子邮件复制到挑选目录，然后通过本地   Internet   信息服务   (IIS)   传送。    
            //SpecifiedPickupDirectory 将电子邮件复制到 SmtpClient.PickupDirectoryLocation 属性指定的目录，然后由外部应用程序传送。  
            mailClient.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;


            //创建邮件对象            MailMessage mailMessage =new MailMessage(from, to, subject, body);

            //定义邮件正文，主题的编码方式            mailMessage.BodyEncoding = System.Text.Encoding.GetEncoding("gb2312");
            mailMessage.SubjectEncoding = System.Text.Encoding.GetEncoding("gb2312");
            //mailMessage.BodyEncoding = Encoding.Default;
            //获取或者设置一个值，该值表示电子邮件正文是否为HTML            mailMessage.IsBodyHtml = IsHtml;

            //指定邮件的优先级            mailMessage.Priority = MailPriority.High;

            //发件人身份验证,否则163   发不了
            //表示当前登陆用户的默认凭据进行身份验证，并且包含用户名密码            mailClient.UseDefaultCredentials =true;
            mailClient.Credentials =new System.Net.NetworkCredential(username, password);

            //发送            mailClient.Send(mailMessage);
            return"发送成功";
        }
        catch (Exception exp)
        {
            return exp.Message;
        }
    }


    //发送plaintxtpublicstaticvoid SendText(stringfrom, string to, string subject, string body, string server, string username, string password)
    {
        SendMail(from, to, subject, body, server, username, password, false);
    }


在你的事件里面调用方法

 SendText("邮箱@163.com", txtMail.Text, "测试一下", "文本", "smtp.163.com", "邮箱@163.com", "密码");