The rule of thumb to prevent email spam is to maintain two e-mail addresses: one you give only to trusted people, the other you expect to get spammed like public mailing lists. Yahoo! Mail now lets you create one extra email address alongside the one you already have. The best part is that both the email accounts can be managed from one common interface.
To add another email address to your Yahoo! account, click on Mail Options and choose Mail Addresses. Remember, you can even use a dot inside your email address names.
Email sent to or from this new address will appear in your mailbox with the rest of your mail. You can send from this new address by selecting it from the pull-down menu when you compose.
You can also sign in to your Yahoo! Mail or Yahoo! Messenger using the new email alias and your old password. The new email address can also be set as the default yahoo email address.