An online archive, also called an archive mailbox or "In-place Archive", is a place where old email messages can be stored so they don't take up space in your primary mailbox.
Email older than a threshold defined by your email administrator may be moved to your online archive automatically to manage the size constraints of a mailbox in relation to the quotas for mailboxes with the Office 365 subscription. Use of the auto-archiving feature is necessary to manage quota usage over the lifespan of our mailboxes.
Accessibility
Your online archive is accessible from the Outlook desktop application and Outlook on the Web. It is not accessible through most mobile application, except through the web browser.
The online archive is present in the same location in the left column where you will find other mailboxes that Outlook is connected to when using the Outlook desktop application .
Outlook Desktop App:
In Outlook on the web you'll find it in the hierarchy of your mailbox on the left column where groups and folders are located.
Outlook on the Web:
Search
The online archive is included in the search indexes of your Outlook desktop application and Outlook on the web.
The folder structure of your online archive will be copied from the folder structure of your primary mailbox as the auto-archive process finds messages to archive.
It is necessary to change the search context to "All Mailboxes" to search your archive mailbox from Outlook's search bar. Alternatively, you can browse through the folders in your online archive and the context of the search bar will follow when it is set to current mailbox or current folder.
Outlook Desktop Application:
Outlook on the Web:
The search context for Outlook on the web is based on the folder your currently viewing. Select a folder from your "In-place Archive" to set the context of your search to your online archive.