C# 邮件地址是否合法的验证

/// <summary>
/// 检测输入的邮件地址strEmail是否合法，非法则返回true。
/// </summary>
public bool CheckEmail(string strEmail)
{
int i, j;
string strTmp, strResult;
string strWords = "abcdefghijklmnopqrstuvwxyz_-.0123456789"; //定义合法字符范围
bool blResult = false;
strTmp = strEmail.Trim();
//检测输入字符串是否为空，不为空时才执行代码。
if (!(strTmp == "" || strTmp.Length == 0))
{
//判断邮件地址中是否存在“@”号
if ((strTmp.IndexOf("@") < 0))
{
blResult = true;
return blResult;
}
//以“@”号为分割符，把地址切分成两部分，分别进行验证。
string[] strChars = strTmp.Split(new char[] { '@' });
foreach (string strChar in strChars)
{
i = strChar.Length;
//“@”号前部分或后部分为空时。
if (i == 0)
{
blResult = true;
return blResult;
}
//逐个字进行验证，如果超出所定义的字符范围strWords，则表示地址非法。
for (j = 0; j < i; j++)
{
strResult = strChar.Substring(j, 1).ToLower();//逐个字符取出比较
if (strWords.IndexOf(strResult) < 0)
{
blResult = true;
return blResult;
}
}
}
}
return blResult;
}

<b>普通的Email验证</b>
<form runat="server">
<table boder="#6699FF">
<tr><td colspan="2" align="center" ><asp:Label id="lblMsgShow" ForeColor="red" runat="server" /></td></tr>
<tr><td>需要验证的Email地址:</td><td><asp:TextBox id="tbEmail" runat="server" /></td></tr>
<tr><td>邮件SMTP服务器：</td><td><asp:TextBox id="tbServer" runat="server" /></td></tr>
<tr><td>SMTP端口：</td><td><asp:TextBox id="tbPort" Text="25" runat="server" /></td></tr>
<tr><td colspan="2" ><asp:Button id="btnValidate" Text="验证" OnClick="Validate_Email" runat="server" /></td></tr>
</table>
<b>验证过程展示：</b>
<asp:Panel id="ShowPro" runat="server" />
</form>
Button控件的点击将激发Valiate_Email事件，所有主程序操作全是在这个事件中完成，下面就来具体讲解本事件处理中的代码。
关于TCP连接的东东，我就不想再重复了。。请大家自己去看我以前的文章:
string strEmail,strServer;
int intPort;
strEmail = tbEmail.Text;
strServer = tbServer.Text;
intPort = Int32.Parse(tbPort.Text); file://默认端口是25
TcpClient tcpc = new TcpClient();

try
{
tcpc.Connect(strServer,intPort);
StreamReader sr = new StreamReader(tcpc.GetStream(),Encoding.Default);
sr.ReadLine();
...
}

file://写入HELO命令
if(OperaStream(tcpc,"HELOhttp://www.webjx.com") != "250")
{
lblMsgShow.Text = "HELO 命令不能完成，本端口可能并非提供SMTP服务";
OperaStream(tcpc,"QUIT");
return;
}
file://写入Mail From命令
if(OperaStream(tcpc,"MAIL FROM: web@webjx.com") != "250")
{
lblMsgShow.Text = "MAIL命令不能完成，SMTP服务需要验证";
OperaStream(tcpc,"QUIT");
return;
}
file://写入RCPT命令，这是关键的一步，后面的参数便是查询的Email的地址
if(OperaStream(tcpc,"RCPT TO: "+strEmail) != "250")
{
lblMsgShow.Text = strEmail + "此邮件地址并非有效";
OperaStream(tcpc,"QUIT");
return;
}
else
{
lblMsgShow.Text = strEmail + "是一个合法有效的邮件地址";
OperaStream(tcpc,"QUIT");
return;
}

public string OperaStream(TcpClient tcpc,string strCmd)
{
Stream TcpStream;
strCmd = strCmd + "/r/n"; file://加入换行符
TcpStream = tcpc.GetStream();
byte[] bWrite = Encoding.Default.GetBytes(strCmd.ToCharArray());
TcpStream.Write(bWrite,0,bWrite.Length);
StreamReader sr = new StreamReader(tcpc.GetStream(),Encoding.Default);
string rl = sr.ReadLine();
string sp = rl.Substring(0,3);
ShowPro.Controls.Add(new LiteralControl("执行命令：<font color=red>"+strCmd+"</font><br/>返回数据："+rl+"<br/>"));
return sp;
}