XF 1.5 Adding checkbox to post form


Active member
Is it possible to add an 'agree' checkbox on the post submission form and what would be the best way to go about this?

I have a classifieds area and when people create their thread I need to have them agree that they have read the related rules and that their post abides by them, otherwise it may be removed without notice.

I'd prefer not to moderate new threads, but that's another option we're looking at.

I couldn't see any maintained add-ons that did anything like this.