(Spam Twitter)-Forum spam is the creating of messages that are advertisements, abusive, or otherwise unwanted on Internet forums. It is generally done by automated spambots.
Types of spam
Forum spambots surf the web, looking for guestbooks, wikis, blogs, forums and any other web forms to submit spam links to. These spambots often use OCR technology to bypass CAPTCHAs present. Some spam messages are targeted towards readers and can involve techniques of target marketing or even phishing, making it hard to tell real posts from the bot generated ones. Not all of the spam posts are meant for the readers; some spam messages are simply hyperlinks intended to boost search engine ranking.
Most forum spam consists of links to external sites, with the dual goals of increasing search engine visibility in highly competitive areas such as weight loss, pharmaceuticals, gambling, pornography, real estate or loans, and generating more traffic for these commercial websites. Some of these links contain code to track the spambot's identity if a sale goes through, when the spammer behind the spambot works on commission.
Flood control: This forces users to wait for a short interval between making posts to the forum, thus preventing spambots from flooding the forum with repeated spam messages.
Some forums employ CAPTCHA (visual confirmation) routines on their registration pages to prevent spambots carrying out automated registrations. Simple CAPTCHA systems which display alphanumeric characters have proven vulnerable to optical character recognition software but those that scramble the characters appear to be far more effective.
Alternative is Textual Confirmation, where the user answers one or more random questions to prove he/she is not a spambot.
Forums have a feature where they send an e-mail to users who registered, either containing the password used to login or an activation code/link.
Some forums have required registration approval where the administrator has to approve accounts.
Authoritative voice: Using an external filtering service, such as Akismet, to get a verdict if the data is spam or not.
Posting limits: Limit posting to registered users and/or require that the user pass a CAPTCHA test before posting.