Is EXO mandatory for Teams retention policy to work

[VigneshGanesan]

Hi Team ,

I’d like to understand the dependency of EXO for Teams retention policies . My customer just wants to use Teams 1:1 chat , group chat , audio calling , video calling and he doesn’t want to use file sharing or meetings /calendar features . So we have decided to turn off EXO and SPO license for the users in the tenant so that they can just use basic Teams features . Since it’s a fintech company they have a 1 day retention policy requirement . AFAIK , 1:1 chat as well as the group chat gets stored in the Office 365 substrate ( i.e . a hidden mailbox )and I’d like to understand whether its mandatory to have an EXO license for a user for the retention policy to work . I understand that the retention policies are directly applied on the Teams chat and this has nothing to do with the user license but I’d still like to double check on this . Could you please confirm this ? @Tony Redmond 

[#2]

@VigneshGanesan 

AFAIK , 1:1 chat as well as the group chat gets stored in the Office 365 substrate ( i.e . a hidden mailbox )

This is incorrect. Teams data stays in Azure. What's in Exchange are compliance records - copies of Teams chats and messages created by the substrate. These items are in user mailboxes (for personal chats and private channel conversations) and group mailboxes (for public channel conversations).

If you want compliance, I think you'll need to have Exchange Online turned on for users. 

[#3]

@Tony Redmond @VigneshGanesan Hi guys, I just waited for Tony to reply as it was an interesting scenario that I never heard of. Usually we just convert a mailbox to a shared mailbox and remove the license/put it on hold. But this was a different request and my guess was that a license is required.

I want to share this table as it describes where Teams data is stored depending on content type. 

https://docs.microsoft.com/en-us/microsoftteams/location-of-data-in-teams#location-of-teams-data-at-... I assume you already know this (but others do read the posts). Cheers!

[#4]

@ChristianBergstrom  Unfortunately some of the language used in that post could be improved. Specifically, sentences like:

"The data is also stored in a hidden folder in the user and group mailboxes to enable Information Protection features."

This creates the impression that Teams data is written into two places. It isn't. The Teams data is in Azure CosmosDB. (Incomplete) copies of messages are captured by the substrate and written into mailboxes. https://www.petri.com/office-365-conversation-records-ediscovery

[#5]

@Tony Redmond @ChristianBergstrom .....Microsoft's documentation states that the chat gets stored in Azure cosmos DB and then gets ingested to Exchange to enable compliance . This makes it looks like there are two copies . Coming to the retention policy piece , it looks like EXO is mandatory for applying the Teams retention policy because when your want to perform an eDiscovery search it gives you an error stating that the user's mailbox is not provisioned . My worry is , what if i don't want to perform an eDiscovery search and I just want to apply a 1 day retention policy ? Is EXO still mandatory ? That's not clear to me yet . 

[#6]

@VigneshGanesan  There are not two copies. Period. There is one copy of Teams data in Azure CosmosDB. 

The compliance records in EXO created by the substrate are mail items. They are imperfect copies of what exists in Teams (no likes or other reactions - see https://office365itpros.com/2019/02/01/teams-compliance-records-focused-on-by-new-report/ for details of a report done on Teams compliance). You should lose the idea that two copies exist.

The problem you face is that Teams builds on many Office 365 components to avoid developing its own functionality. eDiscovery depends on content indexes, which are generated not from Teams but from the contents of the EXO mailboxes. Retention is also based on the contents of EXO mailboxes because it is the Exchange Managed Folder Assistant that processes Teams retention policies against the items stored in the mailboxes. Ergo, you need EXO provisioned to have Teams compliance.

[#7]

@Tony Redmond ....Thanks for clarifying