If you want to easily communicate with all the users at your school, you can create a group for your entire domain. This could be useful for school-wide announcements such as testing schedule or in-service day reminders, monthly events, etc. Instead of entering the name of every user at your school, you can check the box next to Add all users within this domain when you create the group.

All users within yourschool.org will appear as a special entry in the group member list, which you can remove and add back easily. You can apply different sending permissions for this type of group as well.

For example, you can have a school-wide group that only group owners can send mail to – such as an announcement style where only the principals and select faculty can send out mail, or you could create a school-wide list that only members can send mail to – this could be like a 'watercooler' type of list where anyone from the school can send out an email and anyone at the school can read and reply, or even a list where any email address, school or non-school can send mail to.

At your school, you will most likely use the 'announcement' style of school-wide lists, where only a select few owners can send out emails to the entire school.