Spam is one of the major headaches for web masters. Spammers abuse their electronic messaging system; send messages, blog, forum or guestbook or send spam to get free advertising. This issue becomes more serious when they use automated spam program or robot for spamming. So in all modern scripts available today have inbuilt spam-blocking system. Below, I will discuss a little generally accepted anti spam system used by web masters in blocking spam.
Captcha image verification spam blocker
Captcha image verification method is the most popular method to block spam. This method is a form of a text string appears over the photo to return. Users trying to submit messages to enter this verification form text entry field to go through that process. People can easily read the text from the image than automated spam program it is almost impossible to draw the text except good uses OCR (Optical Character Reader) software. By deliberately add some noise and distortion over the captcha image makes it even harder to read. Advantages captcha image verification,
- Only GD library support required to generate Captcha image.
- When designed carefully, this method gives great protection to the spammers loading minimal damage to the users.
- In some poorly designed system noise and distortion are so much improved it will be very difficult to read the text from the image. Confusion arises between small and capital letters that the figures ‘o’ and the digit “0”.
- Visually crafts persons can not through this process.
Question answer method spam blockers
This process is random but simple question appears on the form; the user must enter the correct answer to go through this process. Examples of such questions are, “fire is hot or cold”, “type color of blood”, “add nine with seven”, etc. Advantages of this method include spam blocking,
- This approach is very much user friendly;
- It does not require any special software support to form.
The disadvantage is that it provides a very low protection against spam together CAPTCHA image verification process.
Email and IP ban method spam filtering
You can ‘t prevent spam by banning some email or IP addresses. This method only gives you some extra security. Few webmasters ban a group of IPs from where most spam comes. In such places, if you try to register to post your comments observed first ban notice over IP and request a message to contact the webmaster to overcome these problems. So this filter spam method to filter out spammers and the good users as well.
Whatever the method the ultimate goal of all these methods is to provide a high level of protection for robots without harassing general users. So when you are choosing a spam protection system carefully about the following points.
- System will be browser independent.
- not load too much on the audience to go through the system.
- System should provide maximum security against robots. To avoid trial and error method every time user submit message, refreshes the security question or security image.