phpmailer 6 error Could not instantiate mail function.

[lucavalentino]

Sto tentando di usare per ora solo in locale (XAMPP) l'ultima versione di phpmailer, ma ricevo un errore:

Could not instantiate mail function.

use PHPMailer\PHPMailer\PHPMailer;
  use PHPMailer\PHPMailer\Exception;
  require_once '../include/PHPMailer/Exception.php';
  require_once '../include/PHPMailer/PHPMailer.php';
  require_once '../include/PHPMailer/SMTP.php';
 $mail = new PHPMailer(true);                              // Passing `true` enables exceptions

try {
    $mail->Port = 25;                                    // TCP port to connect to
    $mail->setFrom('email@email.it', 'Mailer');
    $mail->addAddress('email@email.it', 'Joe User');     // Add a recipient
    $mail->isHTML(true);                                  // Set email format to HTML
    $mail->Subject = $oggetto;
    $mail->Body    = $testo;
    $mail->AltBody = 'This is the body in plain text for non-HTML mail clients';    $mail->send();
    echo 'Message has been sent';
} catch (Exception $e) {
    echo 'Message could not be sent. Mailer Error: ', $mail->ErrorInfo;
}