How the Yahoo Account works is a little complicated and it occasionally changes without notice.

Configurations for Yahoo Account and Yahoo Groups
Yahoo Account	Account Info	Other than the accompanying Yahoo email address, you can register up to three alternative email addresses. At least one alternative email address is required. You can specify which email address the Yahoo contacts you (primary email address). You can specify, for each Yahoo Groups you are subscribing, to which email address the messages should be delivered.
	Edit Profile	If you have a Yahoo Account, your Yahoo Profile is automatically created at http://profiles.yahoo.com/your_account_name You can leave it blank or fill in information as you like. Other than the default Yahoo Profile, you can create up to six aliases, which is both convenient and confusing.
Yahoo Groups	My Groups	List of Yahoo Groups you are subscribing.
	Edit My Groups	For each Yahoo Groups you are subscribing, you can specify your profile, email address to deliver messages, or the mode of delivery (individual emails, daily digest, special notices, no email).
	Email Preferences	You can add five alternative email addresses from which you can post messages to Yahoo Groups. For message delivery, you must specify one email address for each Yahoo Groups and this specific email address is always displayed in the message you post, regardless of which email address you post from.

Email Security in the Yahoo Groups

The Yahoo Groups protects your email address in following manners:
1. If you don't post messages at all, your email address will remain "hidden" (except to the moderator).
2. If you post a message, your email address will be revealed to other subscribers, but remain "hidden" to non-subscribers.
3. By "hidden," I mean truncating a vital part of your email address (eg. [email protected] -> bkkriders@y...)