This article will show you how to access your Outlook archive email from a web browser.
All emails, calendar items, and tasks that are older than two years will be moved to your Online Archive folder.
Once emails have been moved to your online archive folder, you will no longer be able to find them in your live email account. You will need to look in your online archive email account for your archived emails.
Log into your email on the Web.
(https://outlook.office365.com)In the folder pane of your email, find and expand your Personal Archive folder.
You can now explore your online archive folders in Personal Archive.