Best Archiving Method for Office 2011 Mailboxes

I have a MAC Client and they user Outlook 2011 and a Cloud Exchange Service for email;  We have a bunch of mailboxes for former employees that I need to archive and delete their mailboxes so they do not get charges for the mailboxes.   The HR department wants to be able to access the information for these users (i.e email, calendar and contacts).   I have set up Accounts for these mailboxes and I can export the mail box but it creates a OLM file extension but it looks like I can only import them in.  Is there anything on the MAC side like windows has with a PST file that you can attach and view the mailbox information?