To view what's in the mailbox, you need to do a Discovery Search.
First you need to ensure you have the Discovery Management role assigned to your mailbox.
Add-RoleGroupMember -Identity "Discovery Management" -Member jsmith
Now you have this, you can perform a Discovery Search through the ECP webpage https://mailserver/ecp
Click on Mail Control - Discovery
Once the search completes, you can open the "Discovery Search Mailbox" using Outlook or OWA (Click on your name and type Discovery Search Mailbox).
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