Random image based verification for new user creation

Hi all,

I'm creating an email list managed by my CMS. I'm wondering if people
had any thoughts about securing it?

I'm just concerned that my application server might be overwhelmed by
requests to add to the list by a spider, etc.

Am I being overly concerned or is that a real possibility? I was
thinking of adding an image with a random sequence of numbers or
letters that people needed to type in a box to prevent this. Does
anyone have any experience with those sorts of things?



I haven't implemented this service yet, but have thought about using
Captchator. Have you looked into Capthchator? http://captchator.com/

I've used recaptcha before and it seemed fine. There's several ruby
gems for integrating with it. I used http://www.loonsoft.com/recaptcha/
you pretty much just have to call the helper function to insert the
right stuff in your view and validate_recap in your controller.