When you go to a box, click on an email thread, and see an error message that says Bad Response From Server, it means one of the follow things has likely happened:
The user who added the thread to the box changed their email address (or renamed it in G Suite)
The user had their Gmail/G Suite account closed
The user revoked Streak's access to their Gmail account
The user deleted the thread from their inbox.
If none of those four items are true, we can help troubleshoot this further, too, at email@example.com.