Parent to Parent Communication

The scenario that comes to mind when I think of a blog as a means to communicate with parents is this: The teacher posts a discussion or relays information about what is going on in the classroom and invites parents to respond or comment. What happens if parents, students, or anyone from the internet, makes inappropriate comments or is just rude to other bloggers? Should there be a set of guidelines on the page to remind users to be respectful of each other? Or should rude comments be deleted? How can this issue be diverted altogether?