Delete them. Someone else with your e-mail address has the virus. Its being sent out with your address as the return address hence you get the return mail.
Update your AV and do a full scan but all you can do is delete them.
What is ransomware and how do I protect my PC from WannaCry?
What I learned from my mentor, Oscar-winning VFX supervisor Phil Tippett
Siri vs Google Assistant
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