Klaviyo signup form email notification using wp_mail

add_shortcode( 'ccom_klaviyo_notify', function() {

	add_action( 'wp_print_footer_scripts', function() {
		?>
		<script type="text/javascript">
		window.addEventListener( 'klaviyoForms', function( e ) { 

			if( e.detail.type != 'submit' ) {
				return;
			}

			if( e.detail.formId != '######' ) {
				return;
			}

			let request = new XMLHttpRequest();
			request.open( 'POST', '/wp-admin/admin-ajax.php', true );
			var data = new FormData();
			data.append( 'action', 'ccom_klaviyo_notify' );
			data.append( 'first_name', e.detail.metaData.$first_name ),
			data.append( 'last_name', e.detail.metaData.$last_name ),
			data.append( 'email', e.detail.metaData.$email ),
			request.send( data );

		} );
		</script>
		<?php
	} );

} );

add_action( 'wp_ajax_ccom_klaviyo_notify', 'ccom_klaviyo_notify' );
add_action( 'wp_ajax_nopriv_ccom_klaviyo_notify', 'ccom_klaviyo_notify' );

function ccom_klaviyo_notify() {

	$args = [
		'to' => '[email protected]',
		'from' => '[email protected]',
		'message' => 'This is a Klaviyo form submission notification.',
		'first_name' => sanitize_text_field( $_POST['first_name'] ),
		'last_name' => sanitize_text_field( $_POST['last_name'] ),
		'email' => sanitize_email( $_POST[ 'email' ] ),
	];

	$mailbody = wpautop(
		sprintf(
			"%s\n\n%s %s\n%s",
			$args['message'],
			$args['first_name'],
			$args['last_name'],
			$args['email']
		)
	);

	$headers = [
		'From: ' . $args['from'],
		'Reply-To: ' . $args['email'],
	];

	wp_mail( $args['to'], $args['subject'], $mailbody, $headers );

	wp_die( 'Success' );

}