Using a url variable, is there a way to display a draft post when not logged in [duplicate]

Question

This question already has an answer here:

• How do I make a draft post accessible to everyone? 6 answers

Is there a method of displaying a post that is a draft when not logged in?

For example I have created a mailer template for my news...

<?php
if ( isset($_GET["mailer"]) )
get_template_part( 'mailers/template', 'news' );
else {
get_header(); ?>

    <!-- WEB TEMPLATE -->

<?php get_footer();
} ?>

This is on my single-news.php template.

As you can see my news mailer template is pulled in when I use this variable... ?mailer

http://www.example.com/my-news-reports/?mailer

But I would like to be able to still use the mailer template even when in draft mode.

Is this possible with adding a variable like this.. ?mailer&draft=true

I understand the 404 template is retrieved, and this may cause issues. Just wondering if there was a method I could adopt to get round this draft issue.

Thanks