Notify notifies the moderator(s) of the forum and the admins if you set it up that way as an admin (you can set that in your profile if you want to be notified or not).

The purpose is as you describe, contact the moderator to notify them about a post. It's easier then using a PM, because the link you get let's you know exactly what post you are notified on. If you have to PM you that stuff, it's kind of a search on what they mean.

With E-Mail post you can e-mail the post. Not per se to fellow board members, but maybe your vacation report to some friends that are not board members.

[Linked Image from siemons.org]