My guestbook keeps being spammed for some reasons.
Sometimes I get similar messages from random people that I don't know.
And they all write same message such as 'thank you very much for your site. It has given me information I need for my school project'. But my website is a personal site. It's about me and my BF and friends. Nothing at all about school projects etc etc. And this very same message will come back again from time to time but from different people.

Another message is sth like 'I love you website. It rocks.' Initially, I thought it might be genuine. But same message keeps coming in from soo many people I never know. So I realised it's a spam.

Now that I realisd it and jus deleted those messages from my guestbook, it's beginnging to get worse.
Now the messages are not HIDDEN spam anymore. They are EXPRESS spam i.e. just long ones with no meaning and nothing...it's just long messages that give sooo many links to 'I dont know where' - I never there to click on those links. I have to keep deleting them. Its really annoying.

I keep getting a similar thing in my blog, some website trying to advertise itself by posting comments. I get a message that says something like this:

Followed by a huge list of links to casinos and all that. My site is not exactly really popular, it's like yours, just a personal site about me and my life. I eventually managed to stop the comments by banning the IP. Also, I have now set it so that if any post contains more than 3 links, I have to approve it first.

Depending on what software you use to run the guestbook, you might be able to do something similar.

For this kind of problem, simple CAPTCHA image sould fix that problem

Or you can make it that if a post has a link you have to approve of it like what rvalkass did but more strict.

Yeah, it appears that this is an ever increasing porblem, my site now has a guestbook link that links to a nice text page that says the 'guestbook is no longer available' or something like that, because I simply could not be bothered with all the spam anymore. Thats just unfortunately the way it is certain individuals, or even 'businesses' feel that this is the best way to convay a message to the rest of the world, I know a favuorite at tmy guestbook was links to drug companies, alright if I ever felt the need to buy drugs for illnesses I don't have (you never know it might be fun) but alot less usefull than the blank space that would have been there alternately.

I have seen software advertised online that is called something like a "Blog Blaster". You buy it and set up a standard message with your links on it, and just push a button, and it posts that same message and links to thousands of blogs all over. This was being hyped as a way to get a bunch of traffic, and lots of links to your site to give the search engines the impression it's popular or important. The ads were bragging about how effective it is to promote your site with. It may not be illegal yet, but it's certainly unethical, and anyone that uses this software should be banned from the search engines permanently.

Wow. That stinks. When ever you get spam, you should just ban the ip and make sure it stays banned. You should also give the banned ip to others having the problem. That way you can reduce the problem. And they get p.o.ed for being banned when not even going there yet. I think its a good idea for the banning part and dumb for people to start adding links and doing things like that.

My site BARELY gets ANY hits, and yet I continue to receive spam messages. I wouldn't rely on IP banning though. I'm a dial-up user, so my IP changes contantly. Also, banning an IP could actually ban someone who DIDN'T do it (I know by experience with MY website). However, I did receive MANY spam messages on the chat board on my site from one IP (plus a comment which I deleted before it showed up). They posted like 15 of the same message, and there was also a spam link on what was supposed to be a petition (that post was deleted). I know how you all feel about spam. I hate it. I just wish that there was some easy way to prevent it that didn't involve banning IP addresses.

I would try a site that shows all the people visiting. Like site meter. they show all the IP's and would let you know if someone is coming several times. Of course, you wouldn't be able to ban them, but you would know. The problem is that it could change. But you would at least have a good idea. Worth a try. Also, do you advertise on traffic exchanges? This means people would come on and leave spam for the fun of it. If you advertise on google or blog, then people would be more genuine when stoping by. Maybe even get a guestbook that requires email to be put in. Most people would fake it, but it might work. Hope this helps. Good luck.