strad wrote:A registration process where you have to copy a set of letters helps get rid of the automated ones, and a registration where the Moderator/s have to process the application , that is get an e-mail to activate the new account, takes to much time for the basic spammer like we have been seeing. The more complex you make joining the more it stops them.
It also provides a barrier to entry for genuine users though. Question is do you think the community on this site is large enough or do you want to encourage new registrations?
Adding a captcha to the registration form isn't too bad, but a lot of these spam services are employing real people (e.g. Amazon mechanical turk) or using tricks (such as displaying the captcha on a different site that people want to access, like a porn or torrent site, and then using their answer on the original site) making the captcha worthless.
You could try asking questions, like in text asking the question "what is six times seven plus three". Or "which is not an f1 team: McLaren, Ferrari, Bob". By having a large set of questions that are unique to your site then you can beat the automated solutions, but it's time consuming to develop and then maintain.
Sharing the workload with the userbase is probably the best way forward. Include a captcha on the registration form just because it's so easy to do and it will weed out some of the sapm, but then allow users to moderate the threads and posts. Limiting this to users with 1,000+ posts still lets you tap up a large number of users on this site and is a large barrier to entry to anyone wishing to abuse the system. Can have a variety of rules like 3 spam reports from 1k+ users and the thread / post is flagged as a priority for the mods and the posting user has their account suspended, 5 spam reports and it's automatically removed.
Also if you really care about SEO and Google then check out http://schema.org
. Pretty much every SEO company on the planet has missed this one but it's the new standard for semantic markup within web pages.