1. You sign up for a group about vintage widgets.
2. Spammer sends a message to your vintage widget list.
3. You get the spam through a whitelisted, opt-in channel.
4. List members & owner get up in arms, flame war ensues over whether the list should be closed or kept open, whether Yahoo isn't doing its job filtering posts, whether it's Yahoo's business to filter posts, etc.
5. Repeat steps 2-4 until the owner decides to limit posting to members.
6. Spammer signs up for Yahoo account, signs up for list, posts spam.
7. Same as step 4.
8. Repeat steps 6-7 until list owner decides to enable some degree of moderation.
One interesting tidbit -- a group I manage used to get hit by Step 6 style spam pretty regularly. I turned on "first post requires moderator approval". Interestingly enough, I haven't had to reject any spam. Apparently just turning on that flag is enough to ward off a lot of spammers.
