Nefunguje mail() na localhoste

<?php
include "conn.php";

$mail = htmlspecialchars($_POST['mail']);
if(isset($_POST['submit'])){
    if(empty($mail)){
        $error = "Nezadali ste e-mail v dobrom tvare.";
        header('Location: mail.php?error='.$error);
}
else {
    function randString($len) {
  $chars = 'abcdefghijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789';
  $str = '';
  for($i = 1, $charLen = strlen($chars); $i <= $len; $i++) {
    $str .= $chars[rand(0, $charLen-1)];
  return $str;
}
}
    $vrateneHeslo = randString(10);
    $subject = "<h1>Obnova hesla</h1><br><p>Vaše nové heslo je </p>" . $vrateneHeslo;
    mail($mail,'Obnovenie hesla',$subject, "From: Private-localhost");

    $error = "Na váš e-mail boli odoslané ďalšie inštrukcie.";
    header('Location: login.php?error='.$error);
    
    }
    }