Description:
Compared to other guestbooks PHPGB is not only feature rich but it was designed from the ground up to deal with the guestbook spammer bots that have become a real nuisance.
Not only does the user need to enter a security code when they submit a guestbook entry - but they also need to verify the guestbook entry via a verification code the user receives in the welcome email or it doesn't show up in the guestbook listing.
This means even if a guestbook spammer bot does manage to make a entry it doesn't really matter as it wont show up as its highly unlikely the guestbook spammer bot has used a real valid working email address and therefore cant or wont be able to verify the guestbook entry. No mysql required.