You want to recover large amounts of “permanently” deleted e-mails from an Office 365 managed e-mail account.
Office 365 with the Outlook Web App (OWA) does not provide a comprehensive way to recover large amounts of deleted e-mails, but there is a fairly simple solution that only requires an installation of Outlook 2013. I am assuming you are a sysadmin that has access to the users mailbox.
- Add the e-mail account to Outlook 2013.
- Right-click on the “Deleted Items” folder in Outlook, and select “Recover Deleted Items…”
- Click the check box at the upper-left of the message list to select all, or use any combination of function keys (Shift, Ctrl, etc.) to select the desired e-mails.
- Press the “recover” button.
The e-mails will be added back to the “Deleted Items” folder, and they can be easily selected in large groups and moved to other folders. At this point if you no longer need that e-mail account in Outlook 2013 you may remove it.