Yahoo's Official Document on Unsubscribing and Continued emails
ID: SLN2468 Refers to: Groups
This article explains why you may still receive emails from a group after trying to unsubscribe.
If you are still receiving email from a group after you have unsubscribed, there are several possible explanations:
Note: Email-only members can only unsubscribe via email, unless they first become a full member of the group by using the Membership Wizard.
In any of these cases, you will have trouble unsubscribing via email. Try unsubscribing from the web, as described above. If that doesn’t work either, please click on the Get Help link on this page.
In groups with more than 400 members: Yahoo! Groups uses a “replicated database” system (for scalability and performance reasons) and sometimes the system gets out of synch. In these situations, Customer Care can help you by “resynching” the database.
You should assume every group of The CT Groups on Yahoo! Groups is over 400 members.