Help - problems with bots taking over my subscribe to newsletter page

[skinnybloke]

Hi - I have a page on my site that allows visitors to subscribe to a newsletter and at the same time get entered into a prize draw.

Over the weekend the amount of subscribers has increased 100 fold. Therefore I assume that there is a bot or something populating the page with email addresses.

Does anyone know of a way that I can stop the bots doing this so that if someone wants to subscribe they will have to physically load that page in their browser.

TIA

[Mike Hughes]

It's not easy if someone's created a bot to do just that.

One way around it is what the search engines are using to prevent automatic submission. Create a number of images with codewords embedded in them. Then display one of the images at random and get the subscriber to enter the code from the image. If the code doesn't match that displayed then reject the subscribe form.

Another option could be to build in IP checking (easily done with PHP and MySQL) and limit submision to 1 item per IP address with a 10 minute reset.

[skinnybloke]

thanks Mike

[allen]

The systems which display code words in images don't use preset images. What they do is generate images on the fly with the words in. This way it's impossible to even guess what word will come up next.

You may also have seen that many of these systems now overlay grids or 'scratched' patterns or display broken letters. This is designed to fool bots which are designed to try and 'read' the writing on the image.

HTH

Allen