I just found out that this has happened since March!
Since March 2020, my clients have received a message that my emails bounce from a VALID godaddy email address, simply for having a duplicate automatically sent to an email address that godaddy disconnected in March.
Godaddy never mentioned that this would happen. I just found out today, July 16, 2020.
Godaddy neglected to tell me that a duplicate from my existing email––to an email address that they disconnected––would look like an email address bounce, just for having a "send a copy to" option entered in the VALID email's account.
Advice from a decades-long godaddy customer: check yours for this error to make sure your sent messages don't look like a bounce to others––unknown to you.
*** Please note that I offer free advice on this forum. Please feel free to give me KUDOS on this topic/discussion; mark my comment as ACCEPTED SOLUTION if you believe I've helped solved your issue. Thanks! ***