DRBGuestbook is a free, simple PHP guestbook script. It uses a flat file to store entries, and doesn't require any additional database software. You can receive an e-mail notification whenever someone signs your guestbook, and moderation of posts is supported. The easy-to-use administration interface allows you delete and approve multiple entries at once. The script uses a verification image to reduce the number of spam entries. There is also a customizable filter for blocking posts that contain bad words or come from specific IP addresses. Posts containing HTML code, URLs, or extremely long words can be blocked, and the minimum and maximum comment length is configurable. Flood protection is also included. The pages are XHTML syntax compliant, and compatible with both IE and Firefox. Fonts and colors are easily customizable via a simple CSS style sheet. Date format, time zone, and text such as field labels and warning messages can be customized easily.