I have (had) a five-email list that was used just for testing the inbox placement of our newsletter. Now that list is down to three email addresses. The missing emails are listed as unsubscribed. According to Zoho help, I should have received an unsubscribe confirmation email from Zoho, from where I should be able to add those email addresses back to my list.

These addresses were created for inbox placement. I did not unsubscribe myself from the list. And, no, no one else could or did either.

I have not received the unsubscribe confirmation for either of these addresses, so I am unable to "resubscribe". I am concerned that other some of my  subscribers may be "unsubscribed" in the same fashion. 

How do I add these personal emails addresses back to my test list?