A guestbook can be a great addition to a website. People visiting your website can leave a comment about what they think of the website as a whole and just let you know they stopped by and give you a shout out. But when spammers start posting to your guestbook you may have a problem on your hands that gets out of control fast. Wreaking havoc on your website and getting your site penalized by the search engines.
We’ll first look at how a guestbook is intended to work. A visitor comes to your site and gets the information they want. They then visit the guestbook page and post a message stating they liked your site and the information on XYZ was very good. That’s all great if everyone on the internet were regular people without some sort of hidden agenda. But spammers take guestbooks and try to make them link machines.
A spammer will post on a guestbook especially if it has a place to input HTML or a URL of their website. They may even use an automated tool to do this. They will post links to websites that may be unsavory at best. Usually when a spammer does this they will post links to many sites on one post and then make numerous posts. This does two things to your website: drain pagerank and makes your website part of a “bad neighborhood”. Linking to bad websites and lots of websites from one page can cause your page to be penalized by search engines.
Fortunately there are some steps you can take if you absolutely want a guestbook on your website. First make sure you can set it up to moderate every post. If spammers have already found your guestbook you’ll have to turn off posting until you get it sorted out. You can also set up an image captcha so the spammer will need to enter the code shown to post, this will deter many spammers. Also turn off HTML and if you do allow a link to be posted make sure it is no follow. Once spammers see this they will likely see no need in spamming your guestbook as it won’t help them any.