I want to customise following part in my outlook plugin through c#
<p><a href="https://i.stack.imgur.com/Yd2LB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Yd2LB.png" alt="enter image description here"></a></p>

<p>I want to make a button of send password of my encrypted mail in the red highlighted portion. Please guide me some thing how can I achieve this in my outlook plugin.</p>