spammers :(

can anyone tell me how to stop these chinese people from selling dried fish pickle on my site ? 

my subscribers are messed up and angry coz of it lol

There have been a million ways mentioned on the forums but the best (if you are on a VPS or dedicated) is to install mod_security and block all link posting.

If you're on shared hosting there is also a free mod that lets you choose which countries to allow to join, this isn't a perfect method because a lot of them spoof their IP.

Another method is add a question to the join form that a non-English speaker wouldn't know.

You can change the name of your join form file to stop the bots from finding you.. but you'll have to change the references inside all the files that call it to.