okay, so how do we stop, as in not allow, any of our classmates from posting a message to ALL the classmates at the same time? as administrators (2 of us) we don't want that to be an open option as some people would use it for advertising issues, etc.

There is not a way to limit functionality. I would simply send an email to anyone doing this and let them know that they need to stop or else you can remove their login details from the site so that they no longer have access.

We have a stated policy on our website http://www.sphsaa.org/Web-Rules.htm and removed anything that doesn't comply. On our home page we also ask classmates to use Contact Us to report anything they find offensive. Saying all this up front makes it easier to take care of transgressions.

That is, of course, locking the barn door after the horse is somewhere in the next county. We can delete the offending spam/advertising post, but it's already probably annoyed a lot of people.

There will be those who love the capability to broacast a message to everyone - and those who think that should be a site option that can be turned off. My vote would be for a way to turn that specific function off, and that appears to be available in Preferences, "Post Message to Classmates" - if I interpret the description right.

People can turn off that 'All Classmates Message" notify now if they wish, but...
I have questions about the new notify option: "Someone posts a message to all classmates". What if that is set to "Never" and someone posts a comment in their own profile? Will those subscribed to him/her still get the 'Profile Update (comment posted)' notify as they would expect to?