Email Spoofing From Our Domain?

Just a quick FYI. It’s come to my attention that a spammer may be engaged in spoofing from the Capulet.com domain. The messages appear to come from ‘bcapulete@capulet.com’, but, of course, aren’t actually from us or this domain. We use Gmail for Domains for our email, so it’d be nearly impossible to spam, even if we wanted to.
I suspect the origin of this is coincidental, not malicious. Juliet@capulet.com is a common test email address for Jabber developers, so I’d guess it’s inspired by that.