How to be removed from a group?

I used to belong to a Yahoo group, but quit a few months ago. It does not show as one of my groups anymore, but I continue to get their posts. I have even contacted the moderator and asked her to ban me in order to stop the emails, but she agreed that I did not even appear to be a member, so she could not ban me. That was weeks ago, and yet I continue getting those posts. Please, how can I be totally removed from that group, and not be removed from all my others? Thanks for any ideas.