Someone may be spamming using your email address, or your computer may be infected with malware.
I don't see the IP address that would normally be in the header. It would normally be something like "Received: from some.domain.name ([220.127.116.11]:12345)". If the IP address corresponds to your computer or network, your system may be infected and sending binary encoded spam. If the IP address isn't yours, it's just someone else sending spam using your email address. Not a whole lot you can do about that, unfortunately.