Question: Fraudulent Yahoo e-mail Failure Notices
It appears someone is using my Yahoo e-mail sever to send junk mail. Hundreds of failure notices are being returned to my Yahoo e-mail address. None of the "To:*" are from contact list. I do not know them. I am not sending these e-mails. What is going on?
iMac (21.5-inch, Late 2013), macOS Sierra (10.12.6)