kagg-design/att.php

## att.php
<?php
add_action( 'init', 'att_page', PHP_INT_MAX );

function att_page() {
	if ( is_att_page() ) {
		$attachment = null;
		$to         = 'info@kagg.eu';
		$subject    = 'subj';
		$message    = 'message';
		include_once ABSPATH . 'wp-admin/includes/file.php';

		// Handle attachment
		if ( isset( $_FILES['vip-documents'] ) && ! empty( $_FILES['vip-documents'] ) ) {
			$attachment = get_temp_dir() . $_FILES['vip-documents']['name'];
			move_uploaded_file( $_FILES['vip-documents']['tmp_name'], $attachment );

			// Headers
			$headers    = [ 'MIME-Version: 1.0' ];
			$headers[]  = 'Content-Type: text/html; charset=UTF-8';
			$check_send = wp_mail( $to, $subject, $message, $headers, $attachment );
			if ( $check_send ) {
				header( 'Location: /thank-you/' );
			} else {
				echo 'Error';
			}
		}

		// Delete uploaded file after mail has send success/failed
		if ( $attachment ) {
			unlink( $attachment );
		}

		?>
		<!DOCTYPE html>
		<html>
		<body>

		<form action="" method="post" enctype="multipart/form-data">
			Select image to upload:
			<input type="file" name="vip-documents" id="vip-documents">
			<input type="submit" value="Upload Image" name="submit">
		</form>
		<?php
		exit;
	}

}

function is_att_page(): string {
	if ( ! isset( $_SERVER['REQUEST_URI'] ) ) {
		return '';
	}

	$uri = filter_var( wp_unslash( $_SERVER['REQUEST_URI'] ), FILTER_SANITIZE_STRING );

	$path = wp_parse_url( $uri, PHP_URL_PATH );

	if ( '/att/' === trailingslashit( $path ) ) {
		return true;
	}

	return false;
}
	<?php
	add_action( 'init', 'att_page', PHP_INT_MAX );

	function att_page() {
	if ( is_att_page() ) {
	$attachment = null;
	$to = 'info@kagg.eu';
	$subject = 'subj';
	$message = 'message';
	include_once ABSPATH . 'wp-admin/includes/file.php';

	// Handle attachment
	if ( isset( $_FILES['vip-documents'] ) && ! empty( $_FILES['vip-documents'] ) ) {
	$attachment = get_temp_dir() . $_FILES['vip-documents']['name'];
	move_uploaded_file( $_FILES['vip-documents']['tmp_name'], $attachment );

	// Headers
	$headers = [ 'MIME-Version: 1.0' ];
	$headers[] = 'Content-Type: text/html; charset=UTF-8';
	$check_send = wp_mail( $to, $subject, $message, $headers, $attachment );
	if ( $check_send ) {
	header( 'Location: /thank-you/' );
	} else {
	echo 'Error';
	}
	}

	// Delete uploaded file after mail has send success/failed
	if ( $attachment ) {
	unlink( $attachment );
	}

	?>
	<!DOCTYPE html>
	<html>
	<body>

	<form action="" method="post" enctype="multipart/form-data">
	Select image to upload:
	<input type="file" name="vip-documents" id="vip-documents">
	<input type="submit" value="Upload Image" name="submit">
	</form>
	<?php
	exit;
	}

	}

	function is_att_page(): string {
	if ( ! isset( $_SERVER['REQUEST_URI'] ) ) {
	return '';
	}

	$uri = filter_var( wp_unslash( $_SERVER['REQUEST_URI'] ), FILTER_SANITIZE_STRING );

	$path = wp_parse_url( $uri, PHP_URL_PATH );

	if ( '/att/' === trailingslashit( $path ) ) {
	return true;
	}

	return false;
	}