String builder underline text : <p>How can I underline text in a string builder ?</p>

<pre><code>strBody.Append("be a minimum of 8 characters")
</code></pre>

<p>I can't use HTML  tags </p>

<pre><code>be a minimum of &lt;u&gt;8 characters&lt;/u&gt;
</code></pre>
