After you send a message through MemberHub you're able to view recipient sent and open rates for the emails that are sent out.
If you are an administrator or the sender of a message this information, if available, can be seen below each message on the Messages page inside each hub. Send and open stats are visible for up to one year but not available for messages created prior to November 2016.
Clicking any of the links will pop up a screen where you can see a list of names and times that the email was delivered or opened. You can even search for a name to see if a particular person received and opened a message.