Hi Natalie,
When a user deletes messages from their Deleted Items folder or uses Shift+Delete to permanently delete a mailbox item, the deleted items are copied to a hidden folder in the user’s mailbox. This folder is called Recoverable Items. Items in the Recoverable Items folder are retained for 14 days by default and then purged by Microsoft Exchange.
Please follow steps below to recover deleted items:
Log into OWA->Browse to “Deleted Items”->Right click “Deleted Items”->Choose “Recover Deleted Items”->Select the items you want to recover
More information about recovering deleted items: http://help.outlook.com/en-US/140/ms.exch.owap.RecoverDeletedItems.aspx .
To permanently preserve some date, you can enabled “Litigation Hold” for your mailbox, administrators can use Multi-Mailbox Searches to search your mailboxes for original and modified versions of a mailbox item.
To enable “Litigation Hold”: Log into MOP->Click “Manage” under “Exchange”->Choose the mailbox->Click “Details”->Click “Mailbox Features”->Choose “Litigation Hold” and click “Enable”.
More information about “Litigation Hold”, see this link: http://social.technet.microsoft.com/wiki/contents/articles/9667.office-365-exchange-online-mailbox-litigation-hold.aspx
About two years archive, the time is from the items was modified.
Thanks,
Jacky Ding