Email a group when a post is made?

[storpappa]

I know how to make a forum so groupA can post, groupB cannot post, can reply and can read.
But I want to add another feature - when groupA makes a new thread, an email is sent to all of the members of groupB notifying them of the thread.

I would like to include the link to the thread, at a minimum. It would be nice to have the option to include the thread, and any attachments to the thread.

Any easy way to do this?

Thanks!