Enabling Exchange Online Archive
One big point of confusion I find with people and Exchange in Office 365 is around the concept of an email in-place archive. There are some important things that should be pointed out when it comes to this in-place archive:
1. Every Exchange Online plan (except Kiosk plans) has the ability to have an in-place email archive. (In-Place Archive isn’t included in Exchange Online Kiosk. However, it can be purchased as an add-on through Exchange Online Archiving.)
2. By default, on all plans, the in-place email archive is disabled for all users. An administrator must enable it before it can be accessed.
3. The in-place email archive contents are stored ONLY in the cloud. They are never synced to a desktop like the Inbox is.
4. The in-place archive folders are only available with the Outlook version in the Professional Plus SKU. Other versions of Outlook will not display the archive folders. See:
http://blog.ciaops.com/2011/12/viewing-exchange-archive-folders.html
for more details.
5. Plans that include Exchange Online Plan 2 (E3, E4) have an unlimited archive. Plans that have Exchange Online Plan 1 (P1, P2, M, E1) have a limit of 50GB of storage between the Inbox and the Archive. For example, in Exchange Online Plan 1 you could have a 25GB Inbox and a 25GB Archive, or a 10GB Inbox and 40GB archive. With Exchange Plan 1 the total size of the Inbox combined with the in-place archive cannot exceed 50GB.
This is the process you need to enable the in-place archive via the portal.