This article only applies if you have a Contact-Based email plan. To reset your contact based subscription, click on the My Account link in the top-right corner of the application and select Account Information.
You will find a checkbox near the bottom of the page that you can use to Reset Contacts on your renewal date. Resetting contacts allows you to allocate a new set of addresses to be a part of your unlimited contacts plan.
When you reset your contacts, they will only be reset upon account renewal. It does not take effect immediately!