Yahoo! Groups takes the following steps to help prevent spam abuse:

• Message moderation feature: Group owners can make their groups "moderated." This means owners approve all messages sent to the group, and reject any messages they regard as spam, or just "off topic." Owners can change the group setting to "moderated" by visiting the Management section of the group. If you’re not the owner of the group but feel it could benefit from message moderation, ask the owner to make the group moderated.
• Spam Filtering: By default, all messages posted to your group are routed through SpamGuard. If a message is identified as potential spam, it will be put in a special folder where a group owner or moderator can review and either approve or delete the message.
• Email masking: We mask your email address on the Groups web site to prevent spammers from harvesting them from our site. However, by using the service, your email will become visible to other group members. Please read the details concerning the visibility of your email address.
• Message posting limits: Yahoo! Groups limits the number of posts to a group within a short period of time and also the number of groups which can be posted to simultaneously.
• No blind posts (BCCs) to group owners: BCC message posts are commonly used to spam.
• No generic addresses: Email addresses such as webmaster@domain.com or postmaster@domain.com cannot be used to join a group. Messages from Groups should be personal and should not use email addresses which commonly recycled within an organization. In addition, spammers commonly target these addresses. For all these reasons, we disallow their user on the service.
• Clear opt-out instructions: Information on how to unsubscribe from a group's mailing list is included in all group email messages.
• Email preferences management: You can prevent group owners from adding you to their group or inviting you to join their group by controlling your email preferences. (Note: Links to control your email preferences also appear in group invitations and welcome notifications).