How can I prevent other users from adding me to their groups?

Twice (or more?) now I have received an email saying 'spammer name' has added me to their yahoo group, and of course it gives me an unsubscribe email that requires some 3-ish steps to complete unsubscription. What I'm wondering is (since these emails do seem to originate from a yahoo domain), is there any way that I can tell yahoo to not allow group administrators to add me to their group?

Update

you should upvote if you wish for a solution (even if there isn't currently one) maybe enough votes would eventually draw the attention of someone who could fix it (or get it fixed)

From web app xenoterracide

• The use of either or both of the links under "Report abuse:" at the bottom of the add message is safe (contrary to Frozenskys' comment) because Yahoo! does not harvest addresses in that fashion. Assuming of course that the notice you received actually is from Yahoo (check the link addresses before clicking).

  The first one gives the group management a "black mark". The second one puts a block against further Adds on your email address.

  The other option, if you have or are willing to obtain a Yahoo! account, is to use the My Email Preferences page to uncheck the "Allow group moderators to directly add me to their groups." setting.

  Shal : Here's what Yahoo! Help has to say on the subject: http://help.yahoo.com/l/us/yahoo/groups/original/members/manage/manage-27.html

  xenoterracide : apparently in my case both 'allow direct adds' and 'invitations' was turned on. Thanks for the second link being that I have a yahoo account for IM purposes.
  From Shal