Three Best Ways To Obfuscate Email Addresses

AntiSpam Silvan over at techblog.tilllate.com has done some research results for us on the best ways of obfuscating email addresses on a web page.

The method used involved nine different code snippits and came up with three over a period of one and a half years that received zero spam.

The Three Methods:

Changing the code direction with CSS:
HTML [Show Styled Code]:
```
email@domain.com
```
HTML [Show Plain Code]:
1. <style type="text/css">
2. span.codedirection { unicode-bidi:bidi-override; direction: rtl; }
3. </style>
4. <p><span class="codedirection">email@domain.com</span></p>

Using CSS display:none:
HTML [Show Styled Code]:
```
email@nulldomain.com
```
HTML [Show Plain Code]:
1. <style type="text/css">
2. p span.displaynone { display:none; }
3. </style>
4. <p>email@<span class="displaynone">null</span>domain.com</p>

ROT13 Encryption (using rot13 or str_rot13):
HTML [Show Styled Code]:
```
silvanfoobar's Mail
```
HTML [Show Plain Code]:
1. <script type="text/javascript">
2. document.write("<n uers=\"znvygb:fvyinasbbone10@gvyyyngr.pbz\" ery=\"absbyybj\">".replace(/[a-zA-Z]/g, function(c){return String.fromCharCode((c<="Z"?90:122)>=(cc=c.charCodeAt(0)+13)?c:c-26);}));
3. </script>silvanfoobar’s Mail</a>

See more about this at techblog.tilllate.com. I noticed he didn’t other methods that I’ve seen such as breaking out the email address in a non-visible table, etc.

Have any other tips to obfuscate email addresses? Let us know in the comments.

Oapah Says:
July 21st, 2008 at 7:35 pm
I’m not sure the first one would work too well. Crawlers don’t process CSS, they’ll just so a regex on the pure HTML and find the email address straight away.
Daily Find #91 | TechToolBlog Says:
July 22nd, 2008 at 9:24 am
[...] Best ways to obfuscate email address [...]
meathive Says:
July 23rd, 2008 at 3:02 am
The bots are _slowly_ evolving; a small portion seem to detect the “foo at dot tld” method which I discovered after using that convention on a couple of papers online. Sites often just encode the “@” which may work just dandy but I personally prefer encoding the entire e-mail string with a custom function that outputs those funky HTML char codes.

foo@bar.tld = &#102&#111&#111&#64&#98&#97&#114&#46&#116&#108&#100
Interesting Finds: 2008.07.24 - gOODiDEA.NET Says:
July 23rd, 2008 at 6:53 pm
[...] Three Best Ways To Obfuscate Email Addresses [...]
Richard Says:
August 29th, 2008 at 6:40 am
Yeah, the email address should be entered back to front in the first example.