public bool SendEmailToSupplier(string from, string to, string subject, string body)
    {
        try
        {

            System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage(from, to);
            msg.Subject = subject;
            msg.Body = body;
            msg.BodyEncoding = System.Text.Encoding.GetEncoding("GB2312");
            msg.Priority = System.Net.Mail.MailPriority.High;
            System.Net.Mail.SmtpClient cliect = new System.Net.Mail.SmtpClient("smtp.qq.com");
            cliect.Credentials = new System.Net.NetworkCredential("692500034@qq.com", "********");//登陆的邮箱名和密码
            cliect.Send(msg);
            return true;
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
            return false;
        }
    }

using System; 
using System.Net.Mail; 
using System.Net; 

/// <summary> 
/// 说明：在.net2.0以上版本中发送电子邮件的方法示例 
/// 用到的类主要位于System.Net.Mail和System.Net命名空间下 
/// 作者：周公 
/// 日期：2008-08-08 
/// 首发地址：http://blog.csdn.net/zhoufoxcn 
/// </summary> 
public class SendMail2 
{ 
    public SendMail2() 
    { 
    } 

    /// <summary> 
    /// 发送邮件 
    /// </summary> 
    /// <param name="to">收件人邮件地址</param> 
    /// <param name="from">发件人邮件地址</param> 
    /// <param name="subject">邮件主题</param> 
    /// <param name="body">邮件内容</param> 
    /// <param name="username">登录smtp主机时用到的用户名,注意是邮件地址'@'以前的部分</param> 
    /// <param name="password">登录smtp主机时用到的用户密码</param> 
    /// <param name="smtpHost">发送邮件用到的smtp主机</param> 
    public void Send(string to, string from, string subject, string body, string userName, string password, string smtpHost) 
    { 
        MailAddress from = new MailAddress(from); 
        MailAddress to = new MailAddress(to); 
        MailMessage message = new MailMessage(from, to); 
        message.Subject = subject;//设置邮件主题 
        message.IsBodyHtml = true;//设置邮件正文为html格式 
        message.Body = body;//设置邮件内容 
        SmtpClient client = new SmtpClient(smtpHost); 
       [color=#FF0000] //设置发送邮件身份验证方式 
        //注意如果发件人地址是abc@def.com，则用户名是abc而不是abc@def.com [/color]
        client.Credentials = new NetworkCredential(userName, password); 
        client.Send(message); 
    } 
}