e-mail SMTP verification

Question

I'm seeking guidance on email SMTP verification.

I attempted to use PHPMailer to identify invalid recipients, but it wasn't successful. I also used sockets, but I get the same response even when the user doesn't exist.

Can anyone provide a solution to resolve this issue? Your help is much appreciated.

Thanks!

function rcpt($recipient)
{
    fputs($this->smtp_conn, "MAIL FROM: <[email protected]>\r\n");
    echo "FROM " . fgets($this->smtp_conn, 1024);
    fputs($this->smtp_conn, "RCPT TO: <$recipient>\r\n");
    echo "TO " . fgets($this->smtp_conn, 1024);

    fputs($this->smtp_conn, "QUIT\r\n");
    echo "QUIT: " . @fgets($this->smtp_conn, 1024);
    fclose($this->smtp_conn);
}
function verifySMTP($email){
try {
    $mail = new PHPMailer(true);

    $mail->isSMTP();
    $mail->Host = 'smp.server.fr';
    $mail->SMTPAuth = true;
    $mail->Username = '[email protected]';
    $mail->Password = 'password/password';
    $mail->SMTPSecure = 'ssl';
    $mail->Port = 465;
    $mail->SMTPDebug = 3;
    $mail->setFrom('[email protected]', 'sender');
    $mail->CharSet = 'UTF-8';
    $mail->SetLanguage('en', 'phpmailer/language/');
    // Email content
    $mail->isHTML(true);
    $mail->Subject = 'Test Subject';
    $mail->Body = 'This is a test email message.';


    if ($mail->smtpConnect()) {
        return  $mail->getSMTPInstance()->rcpt($email);
    } else {
        echo $mail->ErrorInfo;
        $mail->smtpClose();
    }
} catch (\Throwable $ex) {
    throw $ex;
}

}