用c#的SmtpMail发mail我的smtp server需要身份验证怎么办？

我没有看到在什么地方有设置smtp发送mail的用户名和密码的设置
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According to [email protected] (Bill Cheng (MS))

Currently there is no way to specify properties for authentication with the SmtpMail namespace. Try a third party component: http://www.SmtpDotNet.com/

see
http://groups.google.com/groups?selm=ip2oydMICHA.1956%40cpmsftngxa07&oe=UTF-8&output=gplain
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.net文档里有写这个
不过我是没有通过
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我给你一段我用来发送邮件的代码：
CDO.Message oMsg = new CDO.Message();
oMsg.From = FromTextBox.Text ;
oMsg.To = ToTextBox.Text ;
oMsg.Subject = SubjectTextBox.Text ;
oMsg.TextBody = MessageTextBox.Text ;
oMsg.CC=CCTextBox.Text ;
oMsg.BCC=BCCTextBox.Text ;
string UserName;
string[] username=new String[100];
for(int i=0;i<FromTextBox.Text.Length;i++)
{
if(FromTextBox.Text[i].ToString()!="@")
{
username[i]=FromTextBox.Text[i].ToString();
continue;
}
else
break;
}
UserName=String.Concat(username);

CDO.IConfiguration iConfg;
ADODB.Fields oFields;
iConfg = oMsg.Configuration;
oFields = iConfg.Fields;

oFields["http://schemas.microsoft.com/cdo/configuration/sendusing"].Value=2;
oFields["http://schemas.microsoft.com/cdo/configuration/sendemailaddress"].Value=FromTextBox.Text.ToString() ;
oFields["http://schemas.microsoft.com/cdo/configuration/smtpuserreplyemailaddress"].Value=FromTextBox.Text.ToString() ;
oFields["http://schemas.microsoft.com/cdo/configuration/smtpaccountname"].Value=UserName;
oFields["http://schemas.microsoft.com/cdo/configuration/sendusername"].Value=UserName;
oFields["http://schemas.microsoft.com/cdo/configuration/sendpassword"].Value=PasswordTextBox.Text.ToString();
oFields["http://schemas.microsoft.com/cdo/configuration/smtpauthenticate"].Value=1;
oFields["http://schemas.microsoft.com/cdo/configuration/smtpserver"].Value="online.sh.cn";
oFields.Update();

try
{
oMsg.Send();
oMsg = null;
MessageBox.Show("邮件发送成功！");
}
catch (Exception ex)
{
MessageBox.Show("邮件发送不成功！");
}