问可以使用localhost发送带有PHPMailer的邮件，但不能从服务器发送

EN

<?php
require("PHPMailer/src/PHPMailer.php");
require("PHPMailer/src/SMTP.php");
if(!isset($_POST['name']) AND !isset($_POST['mail']) AND !isset($_POST['subjet']) AND !isset($_POST['message'])){
echo '<form method="post" action="contact.php">';
echo '<p><label for="name">Your name</label></p>';
echo '<p><input type="name" name="name" id="name" maxlength="50" placeholder="Name" autofocus required/></p>';
echo '<p><label for="mail">Your e-mail address</label></p>';
echo '<p><input type="email" name="email" id="email" maxlength="250" placeholder="mail@mail.com" required/></p>';
echo '<p><label for="subjet">Sujet</label></p>';
echo '<p><input type="text" name="subject" id="subject" maxlength="250" placeholder="Subject"/></p>';
echo '<p><label for="message">Your message</label></p>';
echo '<p><textarea name="message" id="message" maxlength="2000" required></textarea></p>';
echo '<p><input type="submit" value="Send"/></p>';
echo '</form>';
}elseif(isset($_POST['name']) AND $_POST['name']!=NULL
    AND isset($_POST['email']) AND $_POST['email']!=NULL
    AND isset($_POST['subject'])
    AND isset($_POST['message']) AND $_POST['message']!=NULL{
if($_POST['subject']!=NULL){
  $subject=htmlspecialchars($_POST['subject']);
}
elseif($_POST['subject']==NULL){
  $subject='No title';
}
$mail = new PHPMailer\PHPMailer\PHPMailer();
$mail->IsSMTP();                                // enable SMTP

$mail->SMTPDebug = 2;                           // debugging: 1 = errors and messages, 2 = messages only
$mail->SMTPAuth = true;
$mail->SMTPSecure = 'tls';                      // Enable TLS encryption, `ssl` also accepted
$mail->Host = 'smtp.gmail.com';
$mail->Port = 587;
$mail->IsHTML(true);
$mail->Username = "xxx@gmail.xxx";
$mail->Password = "xxx";
$mail->SetFrom(htmlspecialchars($_POST['email']), htmlspecialchars($_POST['name']));
$mail->AddAddress('xxx@gmail.com', 'First Name    Last Name');
$mail->Subject = $subject;

$mail->MsgHTML(htmlspecialchars($_POST['message']));
if(!$mail->Send()) {
  echo 'Erreur : ' . $mail->ErrorInfo;
} else {
  echo '<script>
          alert("Sent!");
          window.location.replace("contact.php");
        </script>';
}
}
?>