Email Harvesters

Email harvesters are automated software applications which roam the Internet. Like search engine robots, they travel around visiting web pages and gathering information to be stored in a database. Unlike search engines, email harvesters are only looking for email addresses. They are usually sent by spammers and any addresses they find are added to their spam database. Obviously this is a bad thing and you don't want harvesters to find your address.

Email harvesters are common. If your email address is displayed on a web page without protection, it probably won't take long for harvesters to find it. This page outlines some options for protecting against harvesters, with links to more information about each option.

Note: Like most things in web design, dealing with email harvesters is a lot easier if you understand HTML.

How Harvesters Work

Email harvesters look for any string of text which appears to be an email address, such as the examples below. It's important to note that harvesters can recognize email addresses wherever they appear in HTML code — they are not limited to visible text. These examples are all vulnerable:   An email address displayed as text on the page.   An email address which has been made into a hyperlink with code like this:
<a href=""></a>
Click here to email me   An email hyperlink which uses different anchor text, like this:
<a href="">Click here to email me</a>
  An image hyperlink:

<a href="">
<img src="emailme.gif" width="117" height="25" border="0"></a>

How to Deal with Harvesters

There are a number of ways to fend off harvesters, each with their pros and cons. Generally speaking, the easier methods to implement are the most difficult for your visitors to use (and vice versa).

The table below summarises the options. Click each link for more information, or follow the "Next Page" links at the bottom of the page to go through each method in turn.

Cryptic Text
Instead of an email link, you spell out the address in such a way that harvesters won't recognize it. Users must decipher the address and manually enter it into an email.
Recommended For: Temporary web pages, discussion forum messages.
Pros: Very quick and easy to set up.
Cons: Requires some effort from the user. Can be confusing.
Display the address using an image file so harvesters can't see it. Users must manually enter the address into an email.
Recommended For: General purpose.
Pros: Relatively simple to set up.
Cons: Requires some effort from the user. Images must be turned on.
Protect the page containing the address with a password.
Recommended For: Private websites, intranets.
Pros: Can safely include email links. Simple solution for protecting multiple addresses.
Cons: Not very suitable for public websites.
"Encode" the address using JavaScript so harvesters can't see it but real people can.
Recommended For: General purpose.
Pros: Works just like a normal email link. Relatively simple to set up.
Cons: Requires JavaScript to be enabled, so some users may not see it.
Contact Form
A special form on a web page which users fill out to contact you.
Recommended For: Professional websites.
Pros: Flexible, user-friendly, robust and safe.
Cons: Relatively difficult to set up.

Next Page: Cryptic Text