Email bounced back from an unknown name@mydomain

I've had a "mail delivery failed: returning message to sender" message come from mail delivery system, but not to my own email address, to There's also some other domains mentioned in the email that seem to be something to do with verizon and a travel company with a message that I think means the maximum number of bounced emails has been reached which is there to protect against spam. Has someone managed to get an email with my domain and used it to try to send spam? I havent opened the attachments on the email. Thanks for any help.
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