i've used several techniques. Some work on WordPress sites, some work only on PHP/HTML sites. The javascript version allows you to display a normal looking email address in the footer or where ever you want.

FOR HTML SITES USE THIS javascript:
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/* This script and many more are available free online at
The JavaScript Source :: JavaScript Source: Free JavaScripts, Tutorials, Example Code, Reference, Resources, and Help
Created by: Professor :: Professor's Coding Corner */

function mailTo() {
// Copyright 2006 Professional Website Design.
// For other useful scripts and tutorials, see
// Professor's Coding Corner
// You may use or modify the script in any way
// you want, but do not remove the first two
// lines above. Although it's not required, I
// would appreciate an email to let me know
// the URL of the page where you used it.

// The purpose of the mailTo script is to prevent
// email link harvesting by spammer's robots.
// Nothing shows in the file where this is used,
// other than an empty 'span' element. The mailto
// link is added dynamically, and will not show
// up even when you "View Source".

// A user having Javascript disabled will not see
// or be able to use the email link. This is
// necessary in order to achieve the script's
// stated purpose.

// To add a mailto link to your webpage, just:

// 1) Save this script as mailTo.js , or whatever
// else you want to call it. Be sure to include
// the window.onload statement AFTER the function.

// 2) Put the following in the "head" section of
// your webpage:
// <script type="text/javascript" src="mailTo.js">
// </script>

// 3) Put the following code in your webpage wherever
// you want the link to appear.
// <span id="mailTo"></span>

// 4) Substitute your own email address for the one
// in the line below.

var email = "you@yourdomain.com?Subject=Some subject goes here";

var emaildiplay = "you@yourdomain.com";

if (!document.getElementById("mailTo")) return false;

var spanobj = document.getElementById("mailTo");
var anch = document.createElement("a");
var mailto = "mailto:" + email;
anch.setAttribute("href",mailto);
spanobj.appendChild(anch);
var txt = document.createTextNode(emaildiplay);
anch.appendChild(txt);
}

window.onload = mailTo;


/* ==== END ===== */



FOR WORDPRESS SITES CONTACT FORM PAGES:
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I recommend the WP-gbcf plug-in, which shows up in your plug-in admin panel as "Secure and Accessible PHP Contact Form v.2.0WP. Obviously, it also comes in flavors that let you use it in non-WordPress sites, as long as your server is using PHP.

Good luck to you.