Every now and then, I see email sent to a discussion list that includes something like the following:
"Please use Reply to All I am not a member of this discussion group."
And sometimes you see something like this instead:
"Please little-R, I am not a member of this discussion group."
I think you can see where I am going with this. If I send a message and you hit Reply, I get the response. If I send a message and you hit Reply to All, I get a response and so does the group. Unless somebody takes the time to manually remove my name from the To line, I get a response. And people are notoriously lazy, so it's extremely unlikely that they would ever do that.
So, the only information that is actually conveyed by this message is that the author doesn't like your little group enough to actually join it, but they sure would like your help right now.