Just this morning I found out my e-mail account sent out spam or someone else’s did using my e-mail address in the from line. It was a "John Doe" has declined your Paypal invoice. The e-mail had a convincing looking e-mail string showing I had sent an invoice from Paypal to someone and they refused to pay. There was a link to click on the verify my account data or re-submit the invoice.
I immediately forwarded the e-mail to the paypal fraud / spoof e-mail department and changed all my passwords.