Exchange Online Archive Mailboxes Move Away from Purview Compliance Portal

Archive Mailboxes Return to Exchange Admin Center

Microsoft 365 notification MC433154 (posted 29 August) brought the not-unexpected news that Microsoft is eliminating the listing of archive mailboxes in the Microsoft Purview compliance portal (Figure 1) and transferring sole GUI responsibility for these objects to the Exchange Admin Center (EAC).

Microsoft says that this will simplify the customer experience. We say that the old Security and Compliance Center (which became the Purview portal) was a convenient resting place for archive mailboxes while Microsoft upgraded the EAC. In any case, it’s the right thing to do because archive mailboxes (which have nothing to do with Outlook’s Archive folder) belong in the EAC. You won’t be able to access the archive page in the Data lifecycle management section of the Purview portal from sometime in October 2022.

Archive mailboxes in the Microsoft Purview Compliance portal
Figure 1: Archive mailboxes in the Microsoft Purview Compliance portal

EAC and Archive Mailboxes

The implementation of the display about information about archive mailboxes is different in EAC, Instead of a dedicated page that lists just user mailboxes with archives, EAC includes the archive status of mailboxes in its Manage mailboxes list. If the status is None, the mailbox doesn’t have an archive. If Active, the mailbox is archive-enabled. EAC includes both user and shared mailboxes in its listing and doesn’t differentiate between mailboxes with enterprise archives and those limited to 50 GB due to the licenses assigned to accounts (Figure 2).

Archive mailboxes (status) listed in the Exchange Admin Center
Figure 2: Archive mailboxes (status) listed in the Exchange Admin Center

To manage the archive for a mailbox from EAC, select the mailbox from the list to view its properties and go to the Others tab (as in other services). Then select Manage mailbox archive. You can enable or disable the archive mailbox here, but you can’t manage an expandable archive (see below).

After they have an archive, users can move items from their primary mailbox into the archive using drag and drop from Outlook. However, this seldom happens, and default archive tags configured in mailbox retention policies and assigned to mailboxes are responsible for moving most items into archive mailboxes. The ability to move items to the archive Is unique to mailbox retention policies and is a good reason to continue using these policies alongside Microsoft 365 retention policies.

Shared mailboxes that are archive-enabled require Exchange Online Plan 2 licenses.

Auto-Expanding Archives

Enterprise archives are called auto-expanding archives. When they introduced the concept of “bottomless” archives in June 2015, Microsoft told customers that ever-expanding archive mailboxes could continue growing ad infinitum. However, operational and technical realties bit, and Microsoft decided to put a 1.5 TB limit on enterprise archives in 2021. Exchange Online constructs the expandable archive by adding new “storage chunks” (auxiliary mailboxes) to the archive. The storage chunks that form the structure are connected together to form a logical structure. Exchange Online adds new storage chunks to an archive automatically when it detects that the existing storage is 90% occupied.

Even if the organization enables expandable archives, mailboxes don’t automatically use this facility. Instead, an administrator must enable it for a mailbox by running the Enable-Mailbox cmdlet. The first command shown below enables the archive. The archive mailbox must be in place before you can transform it into an expandable archive.

Enable-Mailbox -Identity Michael.King -Archive
Enable-Mailbox -Identity Michael.King -AutoExpandingArchive

If you want to assign an archive mailbox to all mailboxes that aren’t already enabled, you can run a command like this:

Get-ExoMailbox -RecipientTypeDetails UserMailbox -Properties ArchiveStatus | Where-Object {$_.ArchiveStatus -eq "None"} | Enable-Mailbox -Archive

While to ensure that all enabled mailboxes use auto-expandable archives, run a command like this:

Get-ExoMailbox -RecipientTypeDetails UserMailbox -PropertySets Archive | Where-Object {$_.ArchiveStatus -eq "Active" -and $_.AutoExpandingArchiveEnabled -eq $False} | Enable-Mailbox -AutoExpandingArchive

Exchange Server doesn’t support expandable archives. If you plan to move a mailbox back to an on-premises server, you should not enable it for expandable archives.

Reporting Archive Mailboxes

The EAC GUI is acceptable for discovering details about small numbers of archive-enabled mailboxes, but PowerShell is a better option to report details of archive mailboxes. This script finds all the archive-enabled user and shared mailboxes and reports how active each archive mailbox is.

[array]$Mbx = Get-EXOMailbox -PropertySets Archive -Properties DisplayName  -RecipientTypeDetails UserMailbox, SharedMailbox -Filter {ArchiveStatus -eq "Active"} | Sort DisplayName
If (!($Mbx)) { Write-Host "No archive-enabled user or shared mailboxes found - exiting" ; break }
Write-Host ("Processing {0} archive-enabled mailboxes" -f $Mbx.count)

$MbxReport = [System.Collections.Generic.List[Object]]::new()
ForEach ($M in $Mbx) {
  Write-Host "Processing" $M.DisplayName
  $Stats = Get-ExoMailboxStatistics -Identity $M.ExternalDirectoryObjectId -Archive
  [long]$QuotaUsed =  $stats.TotalItemSize.Value.toString().Split("(")[1].Split("bytes")[0]
  [long]$Quota = $M.ArchiveQuota.Split("(")[1].Split("bytes")[0]
  $PercentQuotaUsed = ($QuotaUsed/$Quota).ToString("P")
  $ReportLine = [PSCustomObject][Ordered]@{  
   Mailbox      = $M.DisplayName
   UPN          = $M.UserPrincipalName
   Archive      = $M.ArchiveStatus
   ArchiveItems = $Stats.ItemCount
   ArchiveSize  = $Stats.TotalItemSize.Value.toString().Split("(")[0]
   ArchiveQuota = $M.ArchiveQuota.Split("(")[0] 
   PercentUsed  = $PercentQuotaUsed
   Type         = $M.RecipientTypeDetails
$MbxReport | Out-GridView

The output is stored in a PowerShell list, so it’s accessible by piping the list to the Out-GridView cmdlet (Figure 3) or exporting it to a CSV file, Excel workbook, or HTML report.

Reporting the current state of archive mailboxes
Figure 3: Reporting the current state of archive mailboxes

As you can see, some mailboxes have an archive quota of 110 GB. This is because a retention policy or hold applies to these mailboxes. At least, that’s what Microsoft says in its documentation. However, several of these mailboxes have only a 100 GB archive quota and they are very much subject to retention policies.

As a quick test, I created some new mailboxes, put them on litigation hold, and enabled them for archives, and then for auto-expanding archives. The mailboxes all received 110 GB archive quotas. I conclude that older mailboxes that received expandable archives stay at the original 100 GB allocation. Perhaps Exchange Online will lift the quota the next time it adds a chunk to expand the archive.

Move Won’t Make a Difference

I doubt many people knew that the Microsoft Purview Compliance portal featured archive mailboxes and the reported move back to EAC won’t make much difference. Archive mailboxes are back where they should have been all along, even if PowerShell is a better way to manage them at scale.

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