I think it IS fair of the school to have the "invite all" policy. If you don't want to invite the whole class, then all you have to do is mail the invitations. How hurtful to be one of the ones who did not get an invitation when part of the class is all abuzz about the cool party they are going to.

Birthday parties are NOT school activities and invites should NOT come to school. BUT, if you can't follow that simple guideline, then you better invite everybody. Why is that a bad rule? I know a little girl who is rarely invited to parties. She suffers enough without having to watch the "chosen" ones open up their invites and know that she was excluded and that the whole class knows she was excluded.