4) dictionary attack
FWIW, I checked two servers I admin (one with two domains and roughly 8000 messages over the last seven days, one with about 30 domains and roughly 34000 messages over the last seven days), and I didn't see any messages in my maillogs addressed to [EMAIL PROTECTED] That's anecdotal, to be sure, but given that a dictionary attack seems like one of the less-likely scenarios.
