Understanding soft deletion and hard deletion
There are 2 types of deletion in exchange: Soft delete and hard deletion.
Soft Delete: Drop in deleted folder after deletion
Hard Delete: Permanently delete
Messages are hard deleted in the following situations:
1. In Outlook, use Shift+delete to delete messages
2. IMAP4 clients or other clients that do not first place deleted messages in the deleted folder
3. Move mail to PST
Configuring Exchange Servers
Exchange defaults to keep deleted items for 7 days and deleted mailboxes for 30 days. This restriction can be customized by the user.
This setting is based on the mailbox store level, all mailboxes within this mailbox store are affected, but there may be exceptions, so you need to configure at the user level.
Recover Deleted Items in Outlook
All messages deleted in the Deleted Items folder can be restored on the Outlook client. -Soft recovery
The above feature is for soft recovery, and if you want to restore messages in other folders that are deleted using SHIFT + DELETE, you need to modify the Outlook client's registry.
1. Hkey_local_machinesoftwaremicrosoftexchangeclientoptions
2. New DWORD value, named DumpsterAlwaysOn, value 1
3. Restart Outlook
Recovering Deleted Items in OWA
All messages deleted in the Deleted Items folder can be recovered from OWA. -Soft recovery