They usually unsubscribe after they have sent out their message. At least that has been my experience with my Shakespeare Festival Yahoo group.

 

I had one that sent out pornography and left after I deleted it from the web file section and then another one sent out messages about joining another yahoo group and then left immediately.

 

By the way Yahoo tried to delete my Shakespeare Festival Group because of inactivity between seasons.

 

We never send anything out  in the "Off Season" !

 

I promised them no spam when they joined.

 

I had to rush around and copy something from the web page and send it out to keep the group since there was nothing else to send.