Forum Discussion
Mail retention - storage of potential duplicate Data
Thanks for you Answer. But my question is more about the Mailboxsize itself, rather then deleting items.
We force our users to sort their mails into PublicFolders or Groups. We do this by a strickt limited Mailboxsize. Mail retention (as required by law) is done by Journaling right now.
If we move to the retention policies in Microsoft Purview and all the items stay in the Mailboxes, even if they are moved to PublicFolders or M365 Groups, the Mailbox will grow and grow, until the retention policy allows deleting (this is after 10 years for some mails).
Also, an associated online archive is actually a second mailbox, archiving would not free up any space in the primary mailbox. This would mean, that the Microsoft Purview retention policies are not a equal replacement for Journaling Mailboxes.
They aren't, who says they are?
Archiving does work just fine for retention scenarios, it will free up space in the primary mailbox, including within the recoverable items subtree. Same goes for deleting items, as they will eventually end up in recoverable items and then moved to the associated structure in the archive mailbox.
Ok thanks.
To get it right:
If there is a "hold" retention Policy for 10 years, a MRM (legacy) Policy for moving items to the archive counts as "hold" for the items and space in the primary mailbox is freed up?
Further more, deleted items in the recoverable items subtree under a "hold" Policy also get moved to the archive and space in the primary mailbox is freed up if the primary mailbox exceeds 90% of its space?
On the other hand, manually moving items to M365 Groups or PublicFolder count as deleting and are moved to the recoverable items subtree, which again is archived at 90% of the primary mailbox size.
After the 10 years, the recoverable items subtree in the primary mailbox AND the archive is automatically cleaned up, as these items are marked for deleting?
If this is true, this could be a good replacement for Journaling Mailboxes for us.
There is no 90% threshold, not sure where you got that from. Messages that are deleted from the main mailbox end up in the Recoverable items subtree and are kept there for the duration of any holds affecting them. When the mailbox has an Online archive, a retention tag is automatically applied to the Recoverable items, moving items older than 14 days to the Recoverable items subtree within the archive. So in effect, you still get space in the main mailbox freed up, after a while.
Said tag also ensures that the Recoverable item subtree, which has its own quota independent of the "user" quota, does not get filled up with deleted items. Effectively, with the Online archive you get an extra 100GB quota for the main mailbox and 100GB for the Recoverable items (well 30GB by default, but it changes to 100GB when holds are in play). While less common, you can end up with scenarios where the Recoverable items reaches its quota, thus preventing any item deletions. So having that extra quota helps.
This article gives you more detail on how the Recoverable Items construct works: https://learn.microsoft.com/en-us/exchange/security-and-compliance/recoverable-items-folder/recoverable-items-folder
After a hold expires, items held within the Recoverable items subtree "age out" and are permanently deleted (cannot be recovered anymore). Items that remain in the "main" mailbox will only be affected if you configured a "retain for XXX days and delete" type of tag - no automatic deletion happens unless an admin takes action to enable it.