I am trying to find an answer to a question regarding the TotalDeletedItemSize property in both a user's mailbox and their archive. I know, in general terms, the TotalDeletedItemSize in the user mailbox is the mail that is sitting in the user's Deleted folder and is accessible by the user to be recovered by normal means.
What I am trying to find out is if the size of the TotalDeletedItemSize in both the primary mailbox and the archive also includes items that a user has tried to permanently delete while they are under a litigation hold.
If anyone else had the same question, here is the answer direct from MSFT support.
TotalDeletedItemSize - Items in the Recoverable Items folder are retained for 14 days by default and then purged by Microsoft Exchange. When a mailbox is put on litigation hold, the Recoverable Items folder isn't purged and items in this folder are retained indefinitely.
If a user does a hard delete on an email (deleted the email from the deleted items folder) it will then move to the Recoverable Items folder and due to the litigation hold will remain there and be counted in the TotalDeletedItemSize property.