Sometimes you get a bounced message that you didn’t send in the first place and the reason for that is that someone has spoofed your email address. They have formatted an email to appear that it came from you when it really didn’t. They are usually hoping that you’ll click some link in the email to figure out what’s going on and then, yippee, you’re taken to some annoying, perverse or otherwise malicious website.
There’s not much you can do about spoofing. Just delete the emails and hope they get tired of doing it. I did have spoofing become such an issue with my original email address, which I ignorantly used all over the internet when I first started, that I had to quit using that email address.