Has Your Email Address been Spoofed?
I hope not - but if you've ever received junk email from YOURSELF then for sure someone out there is forging (spoofing) your email address. And no, you're not helpless. Take the matter in hand immediately, and protect your valuable email address(es) with an SPF record which will work as both prevention and cure.
Find out about Email Spoofing and using an SPF record to stop it dead