Form abuse - spam - how to avoid it?

I have a form which has been discovered by some abuse script. Every night it posts several spam-messages on my form.

What are the “tricks of the trade” to avoid such activity?

I currently do not have DB or file write permission on the server where this form is located, but if that is necessary it suppose I can get it. My form is integrated in a CMS-system, and it is handled by a PHP-script I have control over.

One idea I have is to add a identifier to the form to prevent it from being submitted more than once from the same IP within a sertain timeframe, but this would require DB / file access. Or maybe sessions could do it?

Use Captcha

That puts me in the right direction.

Quick and good reply, thank you very much! :slight_smile: