How to set ${var_name}
<p>We are developing a mail system, and we would like to allow user to add custom greeting while creating message.. for example, check following...</p>

<p>we will set this variable(var_name) in php.</p>

<pre><code>Hello ${var_name},
This is test message.
</code></pre>

<p>we are not using any framework.</p>
