asp.net发送邮件

1、局域网内发送邮件，可以匿名发送

/**//// <summary>
    /// 发送邮件给会议参加人员
    /// </summary>
    /// <param name="IP"></param>
    /// <param name="from"></param>
    /// <param name="to"></param>
    /// <param name="subject"></param>
    /// <param name="body"></param>
    /// <returns></returns>
    public void SendEmail(string IP,string from, string to, string subject, string body)
    {
        try
        {
            string serverip = string.Empty;
            if(IP.StartsWith("192.168.100"))
                serverip = "192.168.100.20";         
            else              
                serverip = "192.168.0.2";
            if (to.Length > 0 && serverip.Length>0)  //邮箱为空时不发送
            {
                内网发送邮件#region 内网发送邮件
                System.Web.Mail.MailMessage msg = new System.Web.Mail.MailMessage();
                msg.From = from;
                msg.To = to;
                msg.Subject = subject;
                msg.Body = body;
                msg.BodyFormat = System.Web.Mail.MailFormat.Html;
                msg.BodyEncoding = System.Text.Encoding.GetEncoding("GB2312");
                msg.Priority = System.Web.Mail.MailPriority.High;             
                System.Web.Mail.SmtpMail.SmtpServer = serverip;
                System.Web.Mail.SmtpMail.Send(msg);
                #endregion
            }
        }
        catch (Exception ex)
        {
            new Exception(ex.Message);
        }

    }

2、外网发送邮件

/**//// <summary>
    /// 发送邮件给供应商
    /// </summary>
    /// <param name="form"></param>
    /// <param name="to"></param>
    /// <param name="subject"></param>
    /// <param name="body"></param>
    /// <returns></returns>
    public bool SendEmailToSupplier(string from, string to, string subject, string body)
    {
        try
        {
            System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage();
            msg.From = new System.Net.Mail.MailAddress(from, "XX");
            msg.To.Add(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("localhost");
            cliect.Credentials = new System.Net.NetworkCredential("XXX", "123456");//登陆的邮箱名和密码
            cliect.Send(msg);
            return true;
        }
        catch (Exception ex)
        {
            return false;
        }
        return false;

    }