This post highlights the need to understand how retention works in MS Teams, why it may be related to how long you keep emails (including for backup purposes), and why you need to consider all the elements that make up an Office 365 Group when considering how – and how long – to retain content in MS Teams.
Overview of retention in MS Teams
If you are unfamiliar with how retention works with MS Teams, these two related sites provide very useful detail.
The quote below from the second link is relevant to this post:
‘Teams chats are stored in a hidden SubstrateHolds folder in the mailbox of each user in the chat, and Teams channel messages are stored in a hidden SubstratesHolds folder in the group mailbox for a team. Teams uses an Azure-powered chat service that also stores this data, and by default this service stores the data forever. With a Teams retention policy, when you delete data, the data is permanently deleted from both the Exchange mailboxes and the underlying chat service.’
‘Teams chats and channel messages aren’t affected by retention policies applied to user or group mailboxes in the Exchange email or Office 365 groups locations. Even though Teams chats and channel messages are stored in Exchange, they’re only affected by retention policies applied to the Teams locations.’
- One-to-one chat in MS Teams is stored in a hidden folder of the mailbox of each user in the chat. Documents shared in those chats are stored in the OneDrive for Business of the person who shared it.
- Group chat in Team channels is stored in a hidden folder of the mailbox of the associated Office 365 Group – and also in an Azure chat service. Documents are stored in the Office 365 Group’s SharePoint site (other SharePoint site libraries may also be linked in a channel).
Another quote from the same post:
‘In many cases, organizations consider private chat data as more of a liability than channel messages, which are typically more project-related conversations.’
Teams content is kept in mailboxes, retention may be similar
Typically, in the on-premise past, organisations will have backed up their Exchange mailboxes (and possibly also enabled journaling, to capture emails), for disaster recovery, ‘archiving’ and investigations. Unless a decision is made to invest in cloud back-ups, Office 365 retention policies may also be applied to Exchange mailboxes, effectively replacing the need to back them up. Retention policies applied to Exchange mailboxes don’t affect the teams chat folder.
Organisations should probably apply the same retention period to both emails and Teams chats as they do to email mailbox backups now. That is, if mailboxes are typically kept for 7 – 10 years after the person leaves the organisation, then keep the Teams chats for the same period.
Note that, even if a poster deletes an item (if that option is enabled), it will still be retained if there is a retention policy.
Suggestions for retention in MS Teams
As there can be different retention requirements, depending on the subject matter, here are some suggestions for retention:
- One-to-one chat is like email, you will never know everything that is being said or sent. So a single retention policy that mirrors email would be appropriate.
- Teams chat is more likely to be about the subject of the Team, which is based on an Office 365 Group, its own mailbox, and has a SharePoint site. In this case, you could consider a retention policy applied to all Office 365 Groups or specific Groups – for example ‘Project Groups’, then ensure that the retention policy or policies cover all aspects of the Office 365 Group (mailbox, team chat, SharePoint).
- If all the records relating to a particular subject matter (including email, chat and documents) must be retained for 25 years, then you need to understand all the options.
It underscores the need to plan carefully for retention management for all the key workloads in Office 365.