It would be good to anyone who clicks on the email to send one. But, if you look at the source code, you will see a mishmash of letters and numbers, not the actual email address. So, since harvesters look at *source code*, they can't get it (unless they know the 'code' being used to mix it up). It will look perfectly normal in the post though.
For instance, in the post it will say (and look like):
myemail@there.com
But, in the source code it will say:
Code:
<script type="text/javascript">document.write(unescape('%3c%61%20%68%72%65%66%3d%27%6d%61%69%6c%74%6f%3a%6d%79%65%6d%61%69%6c%40%74%68%65%72%65%2e%63%6f%6d%27%3e%6d%79%65%6d%61%69%6c%40%74%68%65%72%65%2e%63%6f%6d%3c%2f%61%3e'));</script>