My PHP Email Code

<?php
// Include config file
require_once "config.php";
use PHPMailer;

// Define variables and initialize with empty values
$username = $password = $confirm_password = "";
$username_err = $password_err = $confirm_password_err = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){

    // Validate username
    if(empty(trim($_POST["username"]))){
        $username_err = "Please enter a username.";
    } else{
        // Prepare a select statement
        $sql = "SELECT id FROM users WHERE username = ?";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $param_username);

            // Set parameters
            $param_username = trim($_POST["username"]);

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                /* store result */
                mysqli_stmt_store_result($stmt);

                if(mysqli_stmt_num_rows($stmt) == 1){
                    $username_err = "This username is already taken.";
                } else{
                    $username = trim($_POST["username"]);
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }

            // Close statement
            mysqli_stmt_close($stmt);
        }
    }

    if(empty(trim($_POST["email"]))){
        $email_err = "Please enter an email.";
    } else{
        // Prepare a select statement
        $sql = "SELECT id FROM users WHERE email = ?";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $param_email);

            // Set parameters
            $param_email = trim($_POST["email"]);

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                /* store result */
                mysqli_stmt_store_result($stmt);

                if(mysqli_stmt_num_rows($stmt) == 1){
                    $email_err = "This email is already in use.";
                } else{
                    $email = trim($_POST["email"]);
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }

            // Close statement
            mysqli_stmt_close($stmt);
        }
    }

    // Validate password
    if(empty(trim($_POST["password"]))){
        $password_err = "Please enter a password.";
    } elseif(strlen(trim($_POST["password"])) < 6){
        $password_err = "Password must have atleast 6 characters.";
    } else{
        $password = trim($_POST["password"]);
    }

    // Validate confirm password
    if(empty(trim($_POST["confirm_password"]))){
        $confirm_password_err = "Please confirm password.";
    } else{
        $confirm_password = trim($_POST["confirm_password"]);
        if(empty($password_err) && ($password != $confirm_password)){
            $confirm_password_err = "Password did not match.";
        }
    }

    // Check input errors before inserting in database
    if(empty($username_err) && empty($password_err) && empty($confirm_password_err) && empty($email_err)){

        // Prepare an insert statement
        $sql = "INSERT INTO users (username, password, email, isEmailConfirmed, token) VALUES (?, ?, ?, ?, ?)";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "ss", $param_username, $param_password, $param_email, $token);

            // Set parameters
            $param_username = $username;
            $param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash
            $param_email = $email
            $token = 'qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM0123456789!$/()*';
            $token = str_shuffle($token);
            $token = substr($str, 0, 10);
            $isEmailConfirmed = "0";

            include_once "PHPMailer/PHPMailer.php";

            $mail = new PHPMailer();
            $mail->setFrom('no-reply@XXX.XXX');
            $mail->addAddress($email, $name);
            $mail->Subject = "Verification Code";
            $mail->isHTML(true);
            $mail->Body = "
            Please follow the link below to verify:<br /><br />

            <a href="http://www.XXX.XXX/confirm?email=$email&token=$token
            ">Verify</a>

            If you cant click the link please copy and paste this link in the browser:<br /><br />

            http://www.XXX.XXX/confirm?email=$email&token=$token
            ";

            if($mail->send()){
                echo "You have been registered! Please visit your email";
			}


            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Redirect to login page
            } else{
                echo "Something went wrong. Please try again later.";
            }

            // Close statement
            mysqli_stmt_close($stmt);
        }
    }

    // Close connection
    mysqli_close($link);
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Sign Up</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css">
    <style type="text/css">
        body{ font: 14px sans-serif; }
        .wrapper{ width: 350px; padding: 20px; }
    </style>
</head>
<body>
    <div class="wrapper">
        <h2>Sign Up</h2>
        <p>Please fill this form to create an account.</p>
        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
            <div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
                <label>Username</label>
                <input type="text" name="username" class="form-control" value="<?php echo $username; ?>">
                <span class="help-block"><?php echo $username_err; ?></span>
            </div>

            <div class="form-group <?php echo (!empty($email_err)) ? 'has-error' : ''; ?>">
                <label>Email</label>
                <input type="text" name="email" class="form-control" value="<?php echo $email; ?>">
                <span class="help-block"><?php echo $email_err; ?></span>
            </div>

            <div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
                <label>Password</label>
                <input type="password" name="password" class="form-control" value="<?php echo $password; ?>">
                <span class="help-block"><?php echo $password_err; ?></span>
            </div>
            <div class="form-group <?php echo (!empty($confirm_password_err)) ? 'has-error' : ''; ?>">
                <label>Confirm Password</label>
                <input type="password" name="confirm_password" class="form-control" value="<?php echo $confirm_password; ?>">
                <span class="help-block"><?php echo $confirm_password_err; ?></span>
            </div>
            <div class="form-group">
                <input type="submit" class="btn btn-primary" value="Submit">
                <input type="reset" class="btn btn-default" value="Reset">
            </div>
            <p>Already have an account? <a href="../login">Login here</a>.</p>
        </form>
    </div>
</body>
</html>