Nine ways to obfuscate e-mail addresses compared

When displaying an e-mail address on a website you obviously want to obfuscate it to avoid it getting harvested by spammers. But which obfuscation method is the best one? I drove a test to find out. Here are the results:

In 2006 I opened nine different e-mail addresses. On this page I published the nine e-mail addresses. But every address has been obfuscated by a different method. I made sure it’s getting indexed by Google by putting a link to that page on the tilllate.com homepage.

Then I waited 1.5 years (see the original post).

For each e-mail address I counted the amount of spam I received. The amount of spam received started by 21MB (for no obfuscation and a total of over 1800 spam mails) and went down to absolutely no spam.

The following three methods are absolutely rock-solid and keep your addresses safe from the harvesters.

1. Changing the code direction with CSS

Here’s how you do it:

<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-wp-preserve="%3Cstyle%20type%3D%22text%2Fcss%22%3E%0Aspan.codedirection%20%7B%20unicode-bidi%3Abidi-override%3B%20direction%3A%20rtl%3B%20%7D%0A%3C%2Fstyle%3E" data-mce-resize="false" data-mce-placeholder="1" class="mce-object" width="20" height="20" alt="&lt;style&gt;" title="&lt;style&gt;" />



<span class="codedirection">moc.etalllit@7raboofnavlis</span>

2. Using CSS display:none

<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-wp-preserve="%3Cstyle%20type%3D%22text%2Fcss%22%3E%0Ap%20span.displaynone%20%7B%20display%3Anone%3B%20%7D%0A%3C%2Fstyle%3E" data-mce-resize="false" data-mce-placeholder="1" class="mce-object" width="20" height="20" alt="&lt;style&gt;" title="&lt;style&gt;" />



silvanfoobar8@<span class="displaynone">null</span>tilllate.com

3. ROT13 Encryption

ROT13 encode the e-mail address with this tool or use the str_rot13 function of PHP and decode it via Javascript.

<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" data-wp-preserve="%3Cscript%20type%3D%22text%2Fjavascript%22%3E%0Adocument.write(%22%3Cn%20uers%3D%5C%22znvygb%3Afvyinasbbone10%40gvyyyngr.pbz%5C%22%20ery%3D%5C%22absbyybj%5C%22%3E%22.replace(%2F%5Ba-zA-Z%5D%2Fg%2C%20function(c)%7Breturn%20String.fromCharCode((c%3C%3D%22Z%22%3F90%3A122)%3E%3D(c%3Dc.charCodeAt(0)%2B13)%3Fc%3Ac-26)%3B%7D))%3B%0A%3C%2Fscript%3E" data-mce-resize="false" data-mce-placeholder="1" class="mce-object" width="20" height="20" alt="&lt;script&gt;" title="&lt;script&gt;" />silvanfoobar's Mail</a>

Thanks, Christoph Burgdorfer for this idea.