are messages on adult Yahoo groups SPAM?

is that a problem? (Posting at Adult Yahoo Groups = Messages)

I have the impression that it is NOT direct emailing.

I have the impression that it is NOT unsolicited emailing.

I have the impression that it is NOT involuntarily received.

I have the impression that it is NOT illegal SPAM.

Is this correct, or incorrect?

Adult Groups or any Groups

are joined voluntarily, AND

Message Delivery is at the control

of any member, both when Joining

and at any time after already a member.

So how can this be in the same category?
(as SPAM or illegal SPAM)

Is it? If so, it's a new one on me.

???