Hotmail account scam, don't reply.

My husband had a similar experience. He started getting dozens of mailer daemon notifications about email from him that was undeliverable. He had not sent any mail to the many addresses specified.

We figured out someone had probably gotten access to his email account and was sending out who knows how many spam or phishing emails from it. There is a phenomenon that I believe is called an "enslaved computer," where other people's computers and memory are fraudulently used in the service of generating such mass mailings. We think we've got the problem resolved now; it remains to be seen if we stop getting mailer daemon notifications.

BTW: He uses mail.com but I don't know if they are particularly prone to such abuses or whether the scammers are so adept they can use anybody's email accounts.

I wish you the best in stopping this abuse of your account.