IP Address Filtering

Ave, I¹ve run into a slight problem. We maintain a Guestbook for our company¹s website. Lately we have been getting a lot of ³Spam² entries into the Guestbook. I added a snippet into the PHP Script & a field in the mySQL database to record the IP Address of posters. However, for the SPAM posts, it records ³Null² instead of an IP Address. I¹m using $REMOTE_ADDR to records the IP. It records IP Addresses of any genuine poster... But NULL for the spam poster. What else can I do to block the SPAM entry? Is there some other Unique Identifier that I can record of the Spam poster and then block him? Thanks, Rahul S. Johari Coordinator, Internet & Administration Informed Marketing Services Inc. 500 Federal Street, Suite 201 Troy NY 12180 Tel: (518) 687-6700 x154 Fax: (518) 687-6799 Email: rahul@informed-sources.com http://www.informed-sources.com