What is the "Not Tracked"List in the Read Receipts details? Why are some people not tracked? 

We track Read Receipts for the Posts, Announcements, Alerts, Student Work, and Messages. The detail of the Read Receipts (Who viewed, Not viewed, Not Tracked) is viewable by the composer of the content and also the recipient of the content.

Note: All teachers & Admins in the system are not tracked for the Read Receipts.

However, only a teacher can always see the list of people who are not tracked in the Read Receipts details. We do not provide any setting for the users to opt-out of tracking. If you are seeing a parent in the Not Tracked list, that means they are a teacher in another class. If that parent is not a teacher and is still listed in Not Tracked list please write to support@bloomz.com and give the names/ emails of the parents listed under the Not Tracked list. Our support team will get back to you.