asp.net发送邮件

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net.Mail;
using System.Text;

public static class EmailOperation
{

sendto发送邮件去向，title：标题，content：内容

    public static string SendEmail(string sendto, string title, string content)
    {
        string str = "";
             try{
                    DataSet ds = myLib.DBHelper.DbHelperSQL.Query("select * from Email");
                    StringBuilder msg = new StringBuilder();
                    //发件人地址
                    string senderAddress = ds.Tables[0].Rows[0]["senderAddress"].ToString();
                    string senderName = ds.Tables[0].Rows[0]["senderName"].ToString();
                    string senderPassword = ds.Tables[0].Rows[0]["senderPassword"].ToString();
                    string host = ds.Tables[0].Rows[0]["host"].ToString();
                    ///////////////////////////////////////////////////
                    string address = sendto;
                    string displayName = "";
                    ///////////
                    MailAddress from = new MailAddress(senderAddress, senderName);
                    MailMessage newMailMessage = new MailMessage();
                    newMailMessage.From = from;
                    newMailMessage.To.Add(new MailAddress(address, displayName));
                    newMailMessage.Body = content;
                    newMailMessage.Subject = title;
                    newMailMessage.BodyEncoding = System.Text.Encoding.UTF8;
                    newMailMessage.IsBodyHtml = true;

                    //设置SMTP服务器地址
                    SmtpClient newclient = new SmtpClient(host);
                    newclient.UseDefaultCredentials = false;
                    //发件人邮箱的用户名和密码
                    newclient.Credentials = new System.Net.NetworkCredential(senderAddress, senderPassword); //发件人的账号和密码
                    newclient.DeliveryMethod = SmtpDeliveryMethod.Network;
                    newMailMessage.Priority = MailPriority.High;  //设置发送级别
                    //发送邮件
                    newclient.Send(newMailMessage);
               
            }
            catch (Exception ex)
            {
                str = ex.Message;
            }
            return str;
      
        }

}

群发：循环发送就可以了(似乎会被认为是垃圾邮件，目前我发送1W多个邮箱，这个方法实属不行)