In order to fight spammers, I'd like to limit the number of threads and posts that authenticated users can create per hour. What is the easiest way to do so?
You can use Node limit module to limit the users form creating nodes.
This is Form project page,
- Per-role node limits
- Per-user node limits
- Per-time interval node limits
- Any combination of the above
- Drupal 6 & 7 compatibility Requires no programming on the part of the administrator
Also look into Honey pot module.
Honeypot uses both the honeypot and timestamp methods of deterring spam bots from completing forms on your Drupal site (read more here). These methods are effective against many spam bots, and are not as intrusive as CAPTCHAs or other methods which punish the user.
Taken form project page:
The module currently supports enabling for all forms on the site, or particular forms like user registration or password reset forms, webforms, contact forms, node forms, and comment forms.