Explanation
Specify mailto: and e-mail address after it for SMTP to start the e-mail program when a link is clicked. You can also specify Subject, etc by putting "?" after e-mail address, but all the e-mail programs don't support them.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=shift_jis">
<title>Sample</title>
</head>
<body>
<h1>Sample</h1>
<p>
Start the e-mail program when the following link is clicked<br>
<a href="mailto:abc@def.com?Subject=test">abc@def.com</a>
</p>
</body>
</html>