This was originally written in May 2002. It was updated in February 2007, April 2014 and January 2017.
Some of you are probably aware of spiders. They are these little programs that surf the internet looking for data. Some spiders assist search engines in helping you find the web page you are looking for. Those are the good spiders. There also exists evil spiders. They jump from web page to web page looking for email addresses. Once they find one, they send it to a database so someone can send you junk email. Not cool.
Hiding In Plain Sight
What we need is a way to display an email address so the reader of a web page can communicate with the web site, yet we also need to hide the address from the spider. The reader and the spider are looking at the same web page but at differently levels. The reader is looking at the browser’s rendering of HTML. The spider is looking at raw HTML.
Three ideas come to mind: ASCII codes, server-side mail forms and images. ASCII codes and images will look like email addresses on the screen, but nothing like an email address in the source code of the HTML document.
Method 1: ASCII
In HTML when you place “&#” in front of the ASCII code of a character the browser will write the character not the ASCII code to the screen. The reader will see the real character and the spider will see the ASCII codes. The ASCII codes won’t look like an email address, so the spiders won’t notice.
- A will render as an uppercase A.
- b will render as a lowercase b
The function below accepts an email address as a parameter and returns a masked email address that is made up of ASCII codes. When the browser writes the codes to the screen it will get converted back to text. Although it’s possible for a spider to read and convert ASCII codes inside the HTML source, it’s probably not that prevalent. The function goes character by character converting the email address. The last step is to merge the masked email address with the HTML mailto: tag. In order to minimize the chances a clever spider might look for the mailto:, this example masks that word as well.
Then you can call that VBScript function from inside an ASP page. For more information email me at <%= maskEmail(“[email protected]”) %>. The above function should be easy enough to convert into your language of choice.
Method 2: Server-side Mail Forms
These are the contact forms you see everywhere these days. The user fills out a form, clicks submit, and hopes it gets to somebody. This is great for the recipient, because their email address never appears on the site. However, some users don’t trust filling out a form and will withhold feedback.
Method 3: Images
Another option is to create an image of our email address.
Write a function that accepts an email address into 3 parts Where the splits happen is not important. Then add code that reassembles the email and launches the email client. How you chop up the email address is up to you. You can also change the sequence of the parameters.
I believe using the above tools over the past 12 years has greatly reduced the amount of SPAM I received. However, these days SPAM filters are much better, so the need for the above code may be fading. Your call.
I created an ASP.NET control version as well, which is available on GitHub.
I am no longer maintaining online tools to generate either an ASCII or Image based version of an email address. There are numerous online, so you will have no problem finding a replacement.
Search ASCII Image Mask (Google Search)
Text to Image Online Generator (Google Search)