For this, enter the required message. When you then click on "Confirmations" (the eye icon), you can see which recipients have already signed the message. If you click on "NOT SIGNED", you will see the recipients who have not yet confirmed the message.
In the app you can see the confirmations even faster. Just slide the message to the left in the inbox. So the button "Confirmed?" appears. If you click on this button, you will also be linked to the confirmation overview.