Every so often, Yammer will send out email notifications about posts you may have missed. While this can be useful, it may also be a little overwhelming. Here's how you can customise which emails you get, and disable them completely if you want.
First, select the gear icon at the top of the page, then select Edit Settings.
Next, select Notifications.
You will be shown a menu of all the email notifications within Yammer. You can use this to tailor your experience.
Once you're happy with your selection, select Save at the bottom of the page.
Alternatively: At the bottom of every Yammer email is an 'Unsubscribe' option. If you use this, it will unsubscribe you from that particular type of email, and this will be reflected in the above menu.