"Failure notice" spam (updated)

In the past week or so, I seem to be getting great amounts of those "failure notice" type mails you get from a mail server when an email could not be delivered. But they are not answers to any mails I've ever sent. I think they are some kind of spam (which is sometimes confirmed in the middle of all the code and tech-talk, "spam likelihood 99%" or such). But they don't have links to any sales pages, so I don't know how they are supposed to work.

Does anybody else notice a rise in this phenomenon?
Know how it works?

Update:
Thanks to commentors. Indeed it seems related to an old email address of mine (maccreator.com) having been used as fake return address on spam. Not long ago I took an old main address off a spam filter service, and I'd forgotten that the other email address was forwarded to that one for filtering.