As old as this thread is, I imagine these people have all found answers or work-arounds by now. But I'm still going to offer two possible ways to lightly obfuscate email addresses that turn up in text. Antispambot converts random characters from the email address into HTML character codes: @, for example instead of @.
If you can embed PHP into your posts (you'll need a plugin to set that up for you), then your anchor link will look like:
<a href="<?php echo antispambot( 'mailto:john@example.com' ) ; ?>">
But if you cannot embed PHP (there are good reasons to keep your plugin overhead low), then simply convert the email address to HTML character codes somewhere off site and cut-and-paste the resultant string into href=" " between the quotes like this href=" mailto:john@example.com" which I got from this encoder.
An alum at The University of Arizona offers you the encoding and a clever little javascript interpreter, if you want to use javascript. Embed the whole thing, unless you need to do it a lot.
<script type="text/javascript" language="javascript">
<!--
// eMail Obfuscator Script 1.31 by Tim Williams - freeware
{ document.write(String.fromCharCode(60, 97, 32, 104, 114, 101, 102, 61, 34, 109, 97, 105, 108, 116, 111, 58, 106, 111, 104, 110, 64, 101, 120, 97, 109, 112, 108, 101, 46, 99, 111, 109, 34, 62, 74, 111, 104, 110, 60, 47, 97, 62))
}
//-->
</script>
<noscript>
</noscript>
