To see who has seen an announcement, go to the Announcements page and look for the announcement in the list. 

Choose Open report from the drop down on the right to see a list of all of your members and when or if they have viewed the announcement. This will show the date they viewed the announcement, whether it was by logging in to Unison.io or by opening the email notification.  

You will also be able to see if any of the emails bounced, meaning they were not delivered to the recipient. 

Clicking the announcement icon in the upper right of this screen will allow you to send a follow up email or text message announcement to the relevant members based on their status.