My domains, ARFunk.com and AndyFunk.org, never send commercial email, and the hosting service I use protects its mail servers from being used by unethical entities to send their unsolicited commercial email (spam).
So how did you get a spam message appearing to be from someone @arfunk.com or @AndyFunk.org?
Unethical businesses send out messages with forged return addresses that appear to have been sent by innocent third parties. It's unfortunately fairly easy to do this — see this Federal Trade Commission (FTC) report. Both the message recipient and the domain that has been forged are victimized — in this case you and me.
And now there is a new wrinkle to this: telephone spam. At least that's what I'm calling it. Unethical businesses are now making telephone calls with "spoofed" Caller-ID — the call shows as being from someone else's number. For about two weeks in 2013 my phone number was being used this way, victimizing both those called and, again, me.
Thank you for your understanding, and my sympathies for any inconvenience this may have caused you.