If you want to modify your daily digest settings in Yammer - it's very easy. You have three options for daily digests: daily, weekly, and never. Given the level of activity on Yammer, this is a great way to keep up with the activity and posts on your favorite networks or groups within your networks.
Log in to Yammer and choose Account->Edit Accounts.
On the left hand side choose Notifications. You will see your networks on the right hand side. Choose the network that you want to modify for digests. You will then have all of the options for how often you want to be notified. You can also set settings here for what items you want to be notified about, such as when you have a new message or a new follower.