Email Masking
   
There are many methods used for masking email address. I list them here, and
also my own method: an accessible email masking method (URL:
modified-email-redirection.html).
   
Method 1: simple text transformation (Obfuscation/Fragmenting)
   
email@domain.com becomes email at domain dot com
   
Advantages: Easy to implement/program. Fairly easy for users to interperate.
Accessible.
   
Disadvantages: Not effective against email-recognition software.
   
This is one of the most common methods of masking an email address. It masks the
email from most small-time spammers who write weak email-recognition software.
However, even an intermediate programmer can write a simple regular expression
that will see through the most complex simple text transformation.
   
Method 2: HTML/CSS transformation (more Obfuscation/Fragmenting)
   
email@domain.com becomes <span style="direction:rtl">moc.niamod@liame</span>
   
Advantages: Easy for users to interperate. Pretty effective against email
recognition software.
   
Disadvantages: Intermediate skills to implement/program. Some methods not
supported by all browsers or browser settings. Only some copy/paste. Some
methods not as effective against email-recognition software. Almost never
accessible.
   
This method is less common than others because it involves an intermediate
knowledge of manipulating HTML and CSS, and requires a degree of cleverness.
Most methods are not accessible, because they require the developer to severely
obscure the code used display the email address so that software cannot
recognize email in the code. The problem is, blind using screen readers will
hear garble.
   
Other ways of implementing this method include a wide variety of other tags and
CSS properties. You can make a table and style it with CSS so that the cells
appear to make just one word, or do the same with several divs. The idea is to
get creative and mask the email. The code should look NOTHING like an email,
even if HTML tags are stripped (programs can do that!).
   
Method 3: Javascript generation
   
email@domain.com becomes

<script type="text/javascript">
    var part1 = "email";
    var part2 = "domain";
    var part3 = "com";
    document.write(part1+"@"+part2+"."+part3);
<script>

   
Advantages: Easy for users to interperate. Very good copy/paste. Highly
effective against email-recognition software.
   
Disadvantages: Intermediate skills to implement/program. Not supported by some
browsers or browser settings. Almost never accessible.
   
This method can be made better by using more complicated or clever scripts. A
good coder can make it next to impossible for even the most powerful
email-recogntion programs to find the email address. A good coder can even use
AJAX to get the email in a secure way from a server-side script, thus avoiding
putting the email in the code in any form. However, it is pretty much impossible
to make this script accessible. Also, the email address will be invisible to
users that don't support JavaScript.
   
Method 4: Email redirection
   
Update: Modified email redirection (URL: modified-email-redirection.html) is now
described more clearly at
http://www.andrewpeace.com/modified-email-redirection.html (URL:
http://www.andrewpeace.com/modified-email-redirection.html).
   
email@domain.com becomes

<img src="x.gif"
        alt="random-address@sneakemail.com (this anti-spam email address changes
weekly)" />

   
Advantages: Highly effective against email-recognition software. Can be
implimented by users with either low- or high-level coding skills. Can be
implimented to require either no maintenence or weekly maintenence, depending on
level of coding skill. 100% accessible. Supported by all browsers.
   
Disadvantages: No copy/paste.
   
Before I give a more in-depth discussion of this method, let me repeat this: the
email redirection method is highly effective, easy to impliment with maintenance
or advanced implimentation with no maintenance, supported by all browsers, and
completely accessible. The only sacrifice: copy/paste support - which users
don't mind as much as you think (use a mailto link instead).
   
Here's how this method works: you create a temporary email address,
random-address@sneakemail.com in the example. This temporary address is set up
to forward to your real email address. Then, you make an image containing your
real email address in text. The image file in the example is x.gif. The image
can have different colors, lines, or random sequences to mask it from
image-reading software. Since the temporary email address is in the alt tag
(could even be in a mailto link), it is readable by screen-readers for the
blind. Also, seeing people using normal browsers can see your real email
address.
   
Now the only problem left is that your temporary email address will get spammed.
Not a problem. Just change the email address periodically. This is not hard to
do by hand. Also, server-side scripts can be set up that do it all seamlessly
and automatically, changing the email address every week or even every day -
before spamming software gets to them.
   
You can create the random email address on your own server, or you can create
one at SneakEmail.com (URL: http://www.sneakemail.com), a free service. If you
choose this option, you need only create a new SneakEmail address every week and
then modify your site accordingly.
   
Note: There are technologies that can read images. However, it is pretty
unlikely that your email address will be found through an image, especially if
you distort the image even a bit. Most image-reading technology is used for
breaking through CAPTCHA's and creating accounts etc. Not many measly spammers
use that kind of technology!!
   
I strongly suggest that you use this method. It is strong, it is easy, and (most
importantly!) it is accessible!
   
Conclusion
   
For further reference, check out the following link. This page shows the results
of a study on fifty different email masking methods, comparing their
effectiveness and accessibility (amoungst other things):
   
http://nadeausoftware.com/.../ (URL:
http://nadeausoftware.com/articles/2007/05/effective_methods_protect_email_addre
sses_spammers#Results)