Carolyn,
When you post to a Yahoo Group, the people in the group cannot see your email address, other than the moderator. The Radiant Recovery moderators never do anything with your email address that would result in you getting spam.

The message is just telling you that if you post to group members directly (to their email addresses) instead of to the adress for the group, then that person would know your email address. That would be true of anyone you send email to.

There are lots of ways that the companies that send spam can get your address. It may have nothign to do with Yahoo.

Hope that helps,
Kitty