Explanation
It's often the case that your e-mail address is detected if "at" symbol (@) exists and alphabetic character exists back and forth of this symbol. So, entity-encoding (@ into #64;) can prevent your e-mail address from being registered in e-mail data bases.
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<!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>
<address>abc@def.com</address>
</p>
</body>
</html>