Yammer periodically sends notification emails containing information about Yammer activity, letting you know about messages received, invitations, updates, and so on.

You can opt out by clicking the unsubscribe link in the bottom of your emails, but in order to change your notification settings across all your Yammer networks, visit the Notifications page.

Follow the link, or:

1. Select the menu in the upper right corner, with the … icon.
2. Select Settings.
3. On the left side, select Notifications.
4. From here, select the network you wish to configure.
5. Choose your notification settings, and select Save.

Thanks to newsletter subscriber Taylor for suggesting this tip.