Microsoft Exchange makes possible in place preservation of email messages. The archiving of relevant emails involves significant costs because of the need for a user to manage the copying or because of the need to purchase software to implement the hold on the email messages.
The LitigationHoldEnabled property of a mailbox will prevent any item in a mailbox from being removed.
The alternate 'in-place hold' will only direct the retention of emails which come up in a search query. A single mailbox can have multiple in-place holds, but no more than 500 search terms can be used.
Using more than 500 terms in a query will cause all content in the mailbox to be preserved. The LitigationHoldEnable property is either set or not. Either type of hold can be set to remain for a specific time period.
Searches can be run on the messages that are subject to in-place holds. While a hold is in place a user will retain the same rights to delete emails. The admin has the option of informing the user that the mailbox is subject to a hold.
Both types of holds use the Recoverable Items folder to preserve emails. So even when SHIFT + DELETE is used or emails are deleted from the Deleted Items folder, the emails are transferred to the Recoverable Items folder. The recoverable items folder is not visible to users. Note that a user does have the option to recover deleted items on the folder tab.