How Many Teams Compliance Records Are in Your Tenant?

Captured by the Substrate and Stored in Exchange Online

Updated 7 June, 2022

The Microsoft 365 substrate captures Teams compliance records as users chat and post messages to channels. Individual records are created for each message in a thread or conversation. The substrate stores the compliance records in Exchange Online mailboxes:

  • Compliance records for personal chats and private channel conversations are in user mailboxes. When guest and federated users participate in chats, the substrate captures compliance records for these users in special cloud mailboxes that are inaccessible to normal client interfaces.
  • Records for regular channel conversations are in the group mailbox of the hosting team.
  • Records for shared channel conversations are in a special cloud mailbox

In all cases, the compliance records are in the TeamsMessagesData folder in the mailbox. Figure 1 shows compliance records in the TeamsMessagesData folder as viewed using the MFCMAPI utility. The text of the message is highlighted in the item properties.

Teams Compliance Records stored in Exchange Online
Figure 1: Teams Compliance Records stored in Exchange Online

Some backup vendors claim that including the compliance records is enough for Teams backup. The biggest issue with this stance is it’s impossible to recreate a chat or channel conversation from compliance records because the records are imperfect copies (aka “digital twins”) of the original messages created purely for compliance purposes. It’s one of the reasons why Teams is such a difficult application to backup.

Exchange Online indexes the compliance records to ensure that they are available for eDiscovery. Other Microsoft 365 services consume compliance records. For instance, communication compliance relies on these records to detect policy violations such as obscenities or threats in Teams conversations.

Accumulating Since 2017

The substrate has captured Teams compliance records since 2017. Since that time, considerable volumes of these records have accumulated unless Microsoft 365 retention policies for Teams control how long records remain in mailboxes. These policies can remove records after one day. In a notable incident in 2020, an error in the settings of a retention policy resulted in the removal of records for the entire KPMG organization.

You don’t need to worry about Teams compliance records. They exist, do a job, and won’t go away unless retention policies are active. And they are helpful in assessing how much data needs to be moved in a tenant-to-tenant migration.

Migrations for Microsoft 365 tenants involve many different types of data from emails to documents to Teams messages. Migrating emails and documents are well-understood challenges, but the API support for moving Teams information is less developed. Knowing how much information must be moved is a starting point. Although imprecise, one way to get an idea of what’s involved is to check how many Teams compliance records exist in the tenant.

Checking Chats

To begin, we can use the Get-ExoMailboxFolderStatistics cmdlet to return the number of records in user mailboxes. Here’s some code to do the job. You can see that we’re checking the Non-IPM part of the mailbox, which holds the folders used for system purposes that are invisible to users.

$Report = [System.Collections.Generic.List[Object]]::new()
[array]$Mbx = Get-ExoMailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited
If (!($Mbx)) {Write-Host "No mailboxes found - exiting" ; break }
ForEach ($M in $Mbx) {
  $Stats = Get-ExoMailboxFolderStatistics -Identity $M.ExternalDirectoryObjectId -FolderScope NonIPM -IncludeOldestAndNewestItems | ? {$_.Name -eq "TeamsMessagesData"}
  $ReportLine = [PSCustomObject][Ordered]@{  # Write out details of the mailbox
       "User"              = $M.DisplayName
       UPN                 = $M.UserPrincipalName
       TeamsItems          = $Stats.ItemsInFolder
       TeamsItemsSize      = $Stats.FolderSize.Split("(")[0]
       NewestItem          = $Stats.NewestItemReceivedDate
       TotalMbxFolderSize  = [math]::Round($TotalMbxsize/1Mb,2)  }
   Write-Host "Mailbox" $M.DisplayName "Teams chats" $Stats.ItemsInFolder

The output will be something like this:

$Report | ft user, teamsitems, newestitem

User                                    TeamsItems NewestItem
----                                    ---------- ----------
Andy Ruth (Director)                         11257 03/05/2022 13:32:11
Ben Owens (DCPG)                            145354 13/05/2022 15:12:51
Ben James                                     7257 23/05/2022 15:12:51
Brian Weakliam (Operations)                   9866 31/05/2022 12:46:53
James Ryan                                   22446 29/05/2022 14:39:34
Chris Bishop                                 11178 28/05/2022 14:39:34
Kim Akers                                     9533 29/05/2022 10:41:57
James Abrahams                               11127 01/06/2022 13:32:11
Tony Redmond                                 16398 01/06/2022 17:02:47

A total for Teams compliance records in user mailboxes is easily found with a command like:

($Report | measure-object teamsitems -Sum).Sum

Remember that the information spans personal and group chats and conversations in private channels. It’s also true that multiple copies of messages exist. For example, every message posted to a group chat involving ten people results in ten copies of the message (one per mailbox for each participant). The same is true for messages posted to conversations in private channels. It’s hard to set a duplication factor, but it’s likely to be in the region of 3-4, depending on the size of the organization (the larger the organization, the more likely it is that multiple people are involved in chats).

Checking Regular Channels

Channel conversations are easier to move than personal chats because only a single copy of each message exists, and they’re owned by the group rather than individual users. The same kind of approach should work for group mailboxes to report the compliance records gathered for conversations in regular channels.

Here’s a version of the code for user mailboxes that finds all group mailboxes used for teams and runs Get-MailboxFolderStatistics for each mailbox.

Select-MgProfile Beta
$Report = [System.Collections.Generic.List[Object]]::new()
[array]$Teams = Get-MgGroup -Filter "resourceProvisioningOptions/Any(x:x eq 'Team')" -All
If (!($Teams)) {Write-Host "No Teams found - exiting" ; break }
ForEach ($T in $Teams) {
  [array]$Stats = Get-MailboxFolderStatistics -Identity $T.Id -FolderScope NonIPM -IncludeOldestAndNewestItems -ResultSize Unlimited | ? {$_.Name -eq "TeamsMessagesData"}
  If ($Stats.Count -ne 0) {
    $ReportLine = [PSCustomObject][Ordered]@{  # Write out details of the mailbox
       "User"              = $T.DisplayName
       UPN                 = $M.Mail
       TeamsItems          = $Stats.ItemsInFolder
       TeamsItemsSize      = $Stats.FolderSize.Split("(")[0]
       NewestItem          = $Stats.NewestItemReceivedDate
       TotalMbxFolderSize  = [math]::Round($TotalMbxsize/1Mb,2)  }
     Write-Host "Team" $T.DisplayName "Teams channel messages" $Stats.ItemsInFolder }
  Else {Write-Host "Can't figure out the Teams data for" $T.DisplayName }

Up to June 7, 2022, a problem existed in that both Get-MailboxFolderStatistics and Get-ExoMailboxFolderStatistics could return a maximum of 1,000 folders. The issue was first noted in May 2022. Microsoft addressed the problem by adding the ResultSize Unlimited parameter to the Get-MailboxFolderStatistics cmdlet. So far, they have not given Get-ExoMailboxFolderStatistics the same capability, possibly because of the different way that this cmdlet interacts with data (the cmdlet uses a REST API, which imply pagination).

Not many mailboxes have more than a thousand folders. However, I recently noticed the appearance of hundreds of folders named SPOOLS_830, SPOOLS_831, SPOOLS_832, etc. in some group mailboxes. The presence of these folders meant that some group mailboxes easily exceeded the 1,000 folder limit. That’s why I use Get-MailboxFolderStatistics instead of Get-ExoMailboxFolderStatistics in the code shown above. When Microsoft adds the -ResultSize Unlimited parameter to Get-ExoMailboxFolderStatistics, I’ll use that instead.

Interestingly, the Graph MailFolders API does not return the TeamsMessagesData folder in the set of folders it finds in the Non-IPM part of mailboxes.

Poking Around to Find Information

It’s always interesting to poke around Microsoft 365 to find out how things work. In this case, we’ve discussed how to report the number of Teams compliance records stored in user and group mailboxes, something that might be useful if you’re ever involved in a tenant-to-tenant migration project.

We also highlighted the upper limit of the Get-ExoMailboxFolderStatistics cmdlet. You’re unlikely to meet the limit in normal operations unless users have been very busy creating folders. I don’t know why so many SPOOLS folders exist in some group mailboxes, but I shall try to find out.

So much change, all the time. It’s a challenge to stay abreast of all the updates Microsoft makes across Office 365. Subscribe to the Office 365 for IT Pros eBook to receive monthly insights into what happens, why it happens, and what new features and capabilities mean for your tenant.

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