You have some minor mistakes, via the if condition "$email->id == ..."
you can target the mails
How to target other WooCommerce order emails
- ‘customer_completed_order’
- ‘customer_processing_order’
- ‘customer_on_hold_order’
- ‘customer_refunded_order’
- ‘customer_reset_password’
- ‘customer_invoice’
- ‘customer_new_account’
- ‘customer_note’
- ‘cancelled_order’
- ‘failed_order’
- ‘new_order’
function woocommerce_email_order_invoice_number( $order, $sent_to_admin, $plain_text, $email ) {
// For 'new order'
if ( $email->id == 'new_order' ) {
// Get post meta
$my_field_name = get_post_meta( $order->get_id(), 'my_field_name', true );
// True and equal to
if ( $my_field_name && $my_field_name == 1 ) {
echo '<p><strong>My custom field: </strong> <span style="color:red;">Is enabled</span></p>';
}
}
}
add_action( 'woocommerce_email_customer_details', 'woocommerce_email_order_invoice_number', 20, 4 );