Confluence sends daily notifications which is a GREAT and very important feature of the product. This is what actually push the knowlege to users.
In an environment of many spaces and active wiki the amount of information is large and only some of the spaces are of interest to a user.
The user should be able to customize the list of spaces for which he receives notification.
It could be in addition to the current daily notifications. So when you don't have time you delete the full and read only the personal while when you have time you go over the full.
The personal one could be based on the spaces the user selected as interesting (this is a feature already exists in Confluence 2.1.x).