I've begun signing up for services using sub-account-names, e.g., myaddress+someservice@gmail.com. I can easily figure out who's spamming me, and who's sold my

I've begun signing up for services using sub-account-names, e.g., myaddress+someservice@gmail.com. I can easily figure out who's spamming me, and who's sold my email address to others (or, perhaps, has been compromised and my passwords should be changed -- or the existence of the account rethought).