Mar 2nd, 2013
The message stack of module provides the a great way to create a highly customized messaging and notification system:
"Message module is Drupal 7's answer to activity-streams and a flexible Messaging & Notifications system.
Subscribe & Notify
- Message notify is the complimenting module that can be used to send regular or multi-lingual emails (or any other delivery mode) that can also be saved for "email log"
- Message subscribe is a subscription system based on Flag module