Best Drupal module for mailing lists? I am working on a Drupal based site for a church and one of the items is a method for each group to have discussions.

I immediately thought OG would be a good fit but after consideration I'm not sure it will be enough by itself.

The goals are:

1.)  Users will be able to join a group or groups.

2.)  Each group will have private content for members only.

3.)  Each group will also have a mailing list for 2-way communication (so I don't believe SimpleNews will work).  Ideally, when a user is approved to join a group they will also be subscribed to that groups mailing list.

OG will be a good fit for the first 2 items.

I'm not sure about the third.  

I've used Mailman in the past but it appears the mailman modules for Drupal are limited to Drupal 6.

What is the best way to achieve this in Drupal 7?
Use the Message module along with the message notify module. Message module is Drupal 7's answer to activity-streams and a flexible Messaging &amp; Notifications system.

http://drupal.org/project/message
http://drupal.org/project/message_notify