When you send an email to more than one person (group emails), Mailtrack isn't currently able to identify who's opened the mail and who hasn't.
We're looking to add a feature to Mailtrack in the near future that will make this possible. In the meantime, however, we recommend that you use Mailtrack Campaign.
With Mailtrack Campaign you can send an individually tracked copy of your email to up to 200 contacts in one hit.
