If mailbox is not renewed and expires, it gets archived for 30 days. During this time, everything within mailbox is saved and can be recovered by renewing it. If mailbox is not renewed within 30 days of its expiration, all content within mailbox is permanently deleted.
How to extend active mailbox:
Go to "My Websites" page;
Click next to your mailbox;
Select from dropdown menu "Extend";
Follow steps in billing form cart to complete Mailbox extending.