A series of Web attacks by spammers have forced a security firm to <A HREF="http://news.bbc.co.uk/1/hi/technology/4990622.stm">end an initiative to curb junk mail.</A> Israeli start-up Blue Security used a variety of tactics to make spammers clean up the lists of addresses to which they sent junk mail. The firm also automatically filled in forms on spammers' Web sites to get names taken off the mailing lists. But escalating attacks from spammers annoyed by the initiative's success has led to its closure.