The emails contain a simple listing of links, grouped by node type, to nodes posted on the site since the last time a digest newsletter was sent out.
The module is an add-on for the Simplenews module.
Unpack in your modules folder (usually /sites/all/modules/) and enable under Administer > Site Building > Modules.
Here are some key features of "Simplenews Digest":
· How frequently the digest newsletter gets sent (days/weeks/months)
· Which newsletter should act as the digest newsletter
· Which node types and taxonomy terms to send
· How node types should be labeled in the newsletter
· What time of day the newsletter should be sent out
· Drupal 5.x
· Drupal Simplenews module