If you previously had a paid Mailsuite (Mailtrack) subscription and later cancelled it, you may notice that you can still see whether an email was opened, but you can no longer view the detailed open history (such as open dates, times, or number of opens) for emails that were sent while you were subscribed.
This detailed tracking history is not lost. If you resubscribe to a paid plan, you will regain access to the full tracking history for those emails, including the ones sent during your previous subscription period.