One of the most common problems faced by many drupal sites is tons of spam, There are either spam users or spam content or spam comments. There are all sort of nasty things that happen by spammers and it is a huge risk to the website’s credibility and growth. Read on for detailed analysis and recommendations on preventing spam

I personally would not visit a forum again if the content is unmoderated and spam. So how do you avoid the spam. There are three methods

Automatically

            Install modules or write code that block the spam users, comments and content For example there is spam.module which uses Bayesian logic to filter content, or Akismet which sends the content to the Akismet for checking via several tests, Akismet is known to be the best method so far for preventing comment spam. Another method is  Bad Behavior which looks for spammer-like activity and blocks those users. The issue with this method is that sometimes genuine users also get blocked thereby creating a negative spiral.

Setup for these types of solutions needs some work and they can slow your site down considerably depending on the amount of spam that you get and the power of your server.

Challenging Users

These includes turing tests like captcha.module which presents a math problem or “numbers embedded in an image, or KittenAuth – the cute alternative, you’re presented 5 images of animals and you pick the kitty. There’s also things you can do in comment.module setup like requiring contact information, or requiring previews.

Catchpa Riddler module will let you ask custom questions to the users during registration and if they answer correctly they are allowed in. This very useful for niche sites since the spammers will not know answer to simple question related to your website’s domain.

Administrators prevent spam

This will require work, but if your site has less traffic this is the most effective way. You can either disallow commenting without approval in admin/access and/or something like Comment Mail which sends an email with approve/deny links to the admin every time a comment is submitted. Or you could have an army of content moderators to delete spam when they find it.

Likewise you can disallow any registration without administration approval.

The main advantage of this method is there are 100% results however the delay in getting approvals may turn down people.

I generally check the user credentials during registration and only allow them to register if they have entered all profile fields. THis method will cut down 95% of spammers. Looking at Profile fields during registration you will deny a whole lot of people. Then I moderate content every 12 to 24 hours and delete spam comments and posts and block the user. This method works for my niche sites very well.

So what is the best way to prevent drupal spam? Well there is no single answer. Based on your problems you will have to select the best answer. It depends on your spam volume, whether you want to block bots or unwanted users, and how much time you can devote to website moderation.

Mollom which is developed by drupal founder is still not mature enough to be used, there are downtimes and sluggisness in response which plague them for now.
Spamcide – Adds a hidden field to forms that only spam-bots will see and fill in. But this will not work for human spammers
Spambot – Checks member details against the Stop Forum Spam system. An effective method but will not work for anonymous posts. So to use this you will have to stop anonymous posting and also be prepared
To me it seems like Bad Behaviour module and Akismet should work for most users and would be the best option to prevent spam