The best solution for a directly clickable link is probably to generate the link in JavaScript, and make sure that the Email address is constructed and not directly embedded in the script itself. I'd recommend a <noscript> section displaying the Email address in an image or including a link to a contact form page as a fallback.

There's a very helpful discussion here, from back in 2005, which covers numerous methods and considerations....

Protecting Email Addresses From Harvesters
http://www.webmasterworld.com/forum39/3858.htm [webmasterworld.com]

My favorite method then was, and still is, the Hiveware Enkoder (note the spelling), created by Dan Benjamin. It's been discussed often on WebmasterWorld, and is one of the standards in the industry.

The Enkoder is a javascript encoder that's more elaborate than most available. The link is clickable if the visitor has javascript enabled. Use it in conjunction with a gif of your email address in noscript. I still haven't seen harvesting bots get past it. The free Enkoder form is available via the "Enkoder" link at hivelogic.com.

There are simpler methods you can use to disguise the text characters in an email address, like using document write or even simple ASCII character equivalents, but conceivably a bot could decode them. I haven't kept score.

A WebmasterWorld site search for either "hiveware" or for the subject line of your post should bring up much related discussion.

Also see Project Honeypot's article on How to Avoid Spambots [projecthoneypot.org...]

I had previously used the javascript method for a long time.

Last year I noticed these supposedly protected email addresses appearing as plain text in the snippet in Google search results. Their protection has been blown by Google.

g1smd - Does that include Hiveware, or just the simpler javascript methods?

What I had in mind was something along the lines of:

<script type="text/javascript">
 em = 'myname' + String.fromCharCode((6*10)+(2+2)) + 'example' + String.fromCharCode((4*10) + (3+3)) + 'com';
 document.write('<a href="mai' + 'lto:"' + em + '">Em' + 'ail Me</a>');
</script>
<noscript>
<a href="contact.html">Contact Page</a>
</noscript>

where the code wouldn't likely be sniffed out by a less sophisticated scraper looking for the low-hanging fruit. There isn't a foolproof way to make a clickable link that will beat players with the capabilities a Google-level player can apply because, in the end, the code has to work. But you can beat most of the scrapers with a bit of determined obfuscation.

>>How can I block the email address on our website from being spidered by automatic boots and sending us spam.

OT. i'm not sure there is an absolute solution, for example i use an email address for various responses to customers that has never been published but over the years it has been spammed, i suspect because it has ended up in the address books of compromised machines (which obviously you have no control over)

They may use OCR methods so this means once a page is indexed they can figure out if emails are printed. IMO the most important thing is not to publish the contact page (or whatever page contains the email address) to spiders. But if you have, you can always change the page/link. Use js or form methods instead of straight links to the contact page. If they can't find it they can't use it.

Of course a human can see it and publish the email no matter which method you use.