Preservation

[Erin Scupham]

Teams retention policies support:

1. Preservation: Keep Teams data for a specified duration and then do nothing
2. Preservation and then delete: Keep Teams data for a specified duration and then delete
3. Deletion: Delete Teams data after a specified duration

By default, Teams chat, channel, and files data are retained forever. A user can delete something, but in the absence of retention policies, Teams data is always archived into Exchange online mailboxes (user and group) and stays there for eDiscovery.

Does this mean preservation policy is enabled since by default (option 1 above)?  Why else would you need to set just a preservation policy?  

[#2]

Where did you copy that from? IMHO it's not very clear and even misleading. Yes, no items will be removed automatically if there is no retention policy in place. And yes, it's actually hard to delete stuff as the TeamChats folder is not exposed in clients. But if the user knows what he's doing, he can certainly delete messages from the folder. So if you need to ensure chat data is kept immutably for some duration, you need the policy.

@Tony Redmond just in case.

[#3]

"Teams data is archived..."  Well, copies of Teams messages sent to channel conversations and chats are stored in Exchange Online mailboxes for eDiscovery/compliance purposes. I wouldn't say archived because that implies they could be retrieved and brought back as live messages. They're copies and not the real thing. But Teams will keep them forever if no one goes near the compliance records. If you want to have control over retention and removal, you use retention policies. Simple.  https://www.petri.com/teams-compliance-records-hybrid-exchange

[#4]

@Vasil Michev Thanks, got it from here:  https://docs.microsoft.com/en-us/microsoftteams/retention-policies and in the FAQ section.

[#5]

@Tony Redmond Thanks.  What do you mean by if .....no one goes near the compliance records?  

Example scenario, we want Teams messages to be kept for discovery purposes.  Since by default conversations are retained forever in absence of retention, we don't need to 'enable' preservation policy. 

That means...

-Messages a user deletes from their teams conversations are available in content/eDiscovery searches

-If the O365 group is deleted, the teams conversations are deleted 30 days post group deletion, at which time they wouldn't be available in discovery? 

However, if we set a retention to preserve content xx years in the Security & Compliance center, the content would be retained if Group is deleted?  Maybe that's the reason to actually set the retention policy to preserve, for the scenario where the Group is deleted?

[#6]

Correct, if the group is deleted, once it goes past it's recycle bin date, the mailbox and the data will be gone unless you have retention/preservation policy on it. Also if your users mailboxes aren't under an retention then they can technically hack into their hidden folders and remove messages that way as well, hence why you want the user mailboxes under it as well if not already.

All the text about nothing happens to the data means, the azure data stays forever, but if someone deletes the Team or individual messages etc. it will be deleted in that case.

[#7]

I guess you can think of it as the user mailboxes case. The default (Exchange) retention policy, or lack of a policy, doesn't automatically delete any messages, so in that sense they are kept for discovery purposes. They are not kept immutably however, so if you need to meet compliance requirements, you put the mailbox on hold. Same applies to Team Chats, with the difference being that it's a bit harder for end users to deliberately get rid of the messages. But they can surely do so, so if you need to meet compliance requirements use holds/preservation.

[#8]

I left feedback on that article to make it a bit more clear btw.

[#9]

@Erin Scupham Despite the fact that the Teams Chat folder is hidden from clients like OWA and Outlook, retention records can be removed by users if they use tools like MFCMAPI. To stop this, you apply a retention policy for Teams. When a policy is in place, any attempt to remove an item will appear to succeed but behind the scenes Exchange will take a copy and keep it in the Recoverable Items\Purges folder.

You don't need a preservation policy. You need a retention policy to keep the items for whatever period your organization dictates. Teams uses special retention policies because those policies only apply to Teams; other Office 365 retention policies apply the same settings to Exchange, SharePoint, OneDrive, etc.