Any way to block guestbook entires?

[Joe S.]

Is there any way to block guestbook entries -- maybe something like e-mail
rules -- if an entry is made by a person with name equal to XXXXX, block the
entry?

I doubt it but thought I'd ask.

There are a couple of assholes who post comments to my guestbook every
couple of days and I'd like to block them. Of course, they'd just change
identity so I guess it's futile.

Thanks anyway.