If you just want to restore some content (emails/data) from exchange DB, then no need to perform full-db-restore. Instead, try and use the SMBR tool. This will allow you to download the 'content' from the exchange DB using standard MAPI protocol . Most importantly, this will avoid having to restore & overwrite the complete exchange database.
SMBR:
https://kb.netapp.com/Legacy/SMBR/How_to_manually_restore_a_single_item_with_SMBR
How to manually restore a single item with SMBR - NetApp Knowledge Base