Once, you have (seemingly) misappropriated an e-mail list. Send one e-mail to the list, and ask who wants to be on your e-mail list which is separate from Jim's. You will then have your own list, and that should be without compaint because each and every one on that list CLEARLY wants to hear from you.
That is hardly any more work than you sending out your opt out message.
BTW, I am on some e-mail lists generated through iHub boards, and I'll be the first to tell you that if I got e-mail from other than the person I signed up on that board for, litigation wouldn't be far off.
You apparently think that the several hundred people on that list can now use it to cross-send e-mails to each other? Who in their right mind would sign up for such a thing?
Anyway, you seem determined to justify what you are doing, no matter what anyone says. I'll suggest you are asking for big trouble when you start making mass mailings.
Good luck to you,
AK
