php 发送邮件与pop3邮件登录代码

function send_msg($to,$subject,$body) {
$send_addr = '[email protected]';   //发送人地址
$header = "from: admin <".$send_addr."> "; //设置email头
ini_set('sendmail_from',$send_addr);
mail($to,$subject,$body,$header);
}

function pop3_login($host,$username,$password)
{
        global $debug;
    if(empty($host)) {
        return false;
    }
    if($debug)
        echo "open hostname: ".$host.",port: ".$port." ";
    $conn = @fsockopen($host,110,$err_no,$err_str,5);
    if(!$conn) {
        return false;
    }
    $ret_info = fgets($conn,1024);
    if(substr($ret_info,0,3) == "+ok") {
                if(login($conn,$username,$password)) {
                        return true;
                }
    }
    return false;
}

function smtp_login($host,$username,$password)
{
        global $debug;
    if(empty($host)) {
        return false;
    }
    if($debug)
        echo "open hostname: ".$host.",port: ".$port." ";
    $conn = @fsockopen($host,25,$err_no,$err_str,5);
    if(!$conn) {
        return false;
    }
    $ret_info = fgets($conn,1024);
    if(substr($ret_info,0,3) == "220") {
          fputs($conn,"helo localhost ");
          if(substr(fgets($conn,1024),0,3) == "250") {
                if(login($conn,$username,$password,25)) {
                        return true;
                }
          }
    }
    return false;
}

function imap_login($host,$username,$password)
{
        global $debug;
    if(empty($host)) {
        return false;
    }
    if($debug)
        echo "open hostname: ".$host.",port: ".$port." ";
    $conn = @fsockopen($host,143,$err_no,$err_str,5);
    if(!$conn) {
        return false;
    }
    $ret_info = fgets($conn,1024);
        if(strpos($ret_info,"ok")) {
                fputs($conn,"a001 login $username $password ");
                $ret = fgets($conn,1024);
                if(strpos($ret,"login ok")) {
                        return true;
                }
        }
        return false;
}