My best estimate, as an ignorant permanent
newbie, is: forget it. The only thing that protects your privacy
is the ethics of your ISP and the sheer volume of boring data. Your email
address is, like, all over the place. Massive address lists are both
buyable and free. Go look for them on the web and you'll find them.
I do not buy names. If you contact me I (sometimes) put your name on my mailing list. If your address was on a Cc: announcement from another dealer, or if your name was on a published mailing list, or if , well, some other possibilities, I might send you an unsolicited announcement.
How do I protect your privacy in my own ineffective way? Simple. I try never to pass on your address once I get it. I've experienced 2 massive privacy failures, wherein the message should have been sent Bcc and got sent Cc by mistake (I swear I clicked the right button, but what good does it do to swear?) I never sell or give away or trade addresses.
That's about it. I try to keep my closet clean, but there is no privacy out there. They could know you're accessing the porn sites, they see you chatting, they can read your email. The only thing that keeps you safe is that they usually don't care.