This won't be a long post. It'll just show you how, as an administrator of a facebook group, you can add people to your group based on email addresses.
It used to be that when you click "invite" you could add people via email addresses, but that's no longer the case.
- Click Settings to edit your group
- in Manage membership click "who is pre-approved to join"
- upload a file containing the email addresses you want to add to the group.
That's it! Happy Group Building!