php如何验证smtp信息的正确

最近在用dede做站，看到后台有启用smtp方式发送邮件的设置，但没有验证。请问各位PHP大神，如何验证填写的smtp信息是否正确，验证包括端口、用户名、密码？求php代码实现，并输出这些错误信息，100分奉上！感谢。

回复讨论(解决方案)

dede的启用smtp方式发送邮件的设置，你是安装的插件吗？
我本地装的最新dede好像没这个功能设置哦

回楼上大牛，我只要能验证smtp信息是否正确就行，不需要做成dede插件。

//打开smtp服务器端口
$fp = @fsockopen($smtp_host, 25);
if (!$fp)
echo "Error: Cannot conect to ".$smtp_host."
";

$smtp = array(	//1、EHLO，期待返回220或者250	array("EHLO ".$loc_host.$lb,"220,250","HELO error: "),	//2、发送Auth Login，期待返回334	array("AUTH LOGIN".$lb,"334","AUTH error:"),	//3、发送经过Base64编码的用户名，期待返回334	array(base64_encode($smtp_acc).$lb,"334","AUTHENTIFICATION error : "),	//4、发送经过Base64编码的密码，期待返回235	array(base64_encode($smtp_pass).$lb,"235","AUTHENTIFICATION error : ")	);		//5、发送Mail From，期待返回250	$smtp[] = array("MAIL FROM: ".$lb,"250","MAIL FROM error: ");	//6、发送Rcpt To。期待返回250	$smtp[] = array("RCPT TO: ".$lb,"250","RCPT TO error: ");	//7、发送DATA，期待返回354	$smtp[] = array("DATA".$lb,"354","DATA error: ");	//8.0、发送From	$smtp[] = array("From: ".$from.$lb,"","");	//8.2、发送To	$smtp[] = array("To: ".$to.$lb,"","");	//8.1、发送标题	$smtp[] = array("Subject: ".$subject.$lb,"","");$result_str="";	//发送smtp数组中的命令/数据	foreach($smtp as $req)	{	//发送信息	@fputs($fp, $req[0]);	//如果需要接收服务器返回信息，则	if($req[1])	{	//接收信息	while($result = @fgets($fp, 1024))	{	if(substr($result,3,1) == " ")	{	break;	}	};	if (!strstr($req[1],substr($result,0,3)))	{	$result_str.=$req[2].$result."
";	}	}	}	//关闭连接	@fclose($fp);	return $result_str;	}

倒没有没弄过验证smtp的端口、用户名、密码，端口还好说，但用户名、密码的话，只能尝试去请求来判断了...

function smtp_sockopen_relay()
{
$this->log_write("Trying to ".$this->relay_host.":".$this->smtp_port."\n");
$this->sock = @fsockopen($this->relay_host, $this->smtp_port, $errno, $errstr, $this->time_out);
if (!($this->sock && $this->smtp_ok()))
{
$this->log_write("Error: Cannot connenct to relay host ".$this->relay_host."\n");
$this->log_write("Error: ".$errstr." (".$errno.")\n");
return FALSE;
}
$this->log_write("Connected to relay host ".$this->relay_host."\n");
return TRUE;;
}