I'm sure this must have been discussed elsewhere, but I have searched and searched and cannot find an answer!

I have a very simple contact form, using Matt's Script (Perl), which is being inundated with spam. To combat this I want to block anyone from submitting links. I thought it would be really easy, but I can't find any information on how to do this. Does anyone know a simple way of blocking submissions that contain the string 'http'? (Using Perl; I don't have PHP)

I have basically zero knowledge of perl, so a piece of code that I can copy and paste would be appreciated!

I have tried using BFormMail, which allows you to block strings, but if I add either 'http' or 'www' to the forbidden strings list it won't allow anything to be submitted. If anyone has knowledge of this that would also be appreciated.

To be clear: I am not looking for any other method of blocking spam; I think Captchas and hidden fields both have drawbacks, and 99% of spam contains links so this seems to me the best way to eliminate it.

Thanks in advance for your help.

Gavin