This article describes how to increase mailbox quota for the Legacy dedicated environment. You should work through the following steps before you contact Microsoft.

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  1. Review the current mailbox size.

    • Active (primary) mailboxes: The size and quota of this mailbox will reflect the size of the assigned plan. This includes the items in the Deleted Items folder. To review the Active mailbox size, run the following cmdlets: 

      Get-MailboxStatistics | fl TotalItemSize,ItemCount,IsArchiveMailbox

      Get-Mailbox | fl IssueWarningQuota,ProhibitSendQuota,ProhibitSendReceiveQuota

    • Recoverable items: This space is separate from the active mailbox, and it includes the Purges and Deletions folders. These are not visible in the mailbox. The Recoverable Items folder replaces the feature that was known as the dumpster in earlier versions of Microsoft Exchange. To view the Recoverable Items size, run the following cmdlets: 

      Get-MailboxStatistics | fl TotalDeletedItemSize,DeletedItemCount,IsArchiveMailbox

      Get-Mailbox | fl RecoverableItemsQuota,RecoverableItemsWarningQuota

    • Archive mailboxes: This space is separate from the active mailbox and has its own Recoverable Items. If an archive is present on the mailbox, the ArchiveGuid value will be non-zero. To review the active mailbox size, run the following cmdlets: 

      Get-MailboxStatistics -archive | fl TotalItemSize,ItemCount,TotalDeletedItemSize,DeletedItemCount,IsArchiveMailbox

      Get-Mailbox -archive | fl IssueWarningQuota,ProhibitSendQuota,ProhibitSendReceiveQuota,RecoverableItemsQuota,RecoverableItemsWarningQuota

  2. If you have to increase the mailbox plan size, review the available size options at Mailbox quotas in Office 365 Dedicated/ITAR and then update the appropriate attributes (MBX=, TYPE=). 

    The largest mailbox plan is as follows:

    MBX=50 GB;TYPE=EP2D2_Dumpster;PA=1

    Primary MBX = 50 GB
    Primary MBX/Recoverable Items = 200 GB
    Archive MBX = 100 GB
    Archive MBX/Recoverable Items = 200 GB

    Total size is effectively 550 GB of storage.

  3. If you change the mailbox plan and need it increased immediately to that size, make sure that the new plan is synced to the managed environment, and then contact Microsoft. For more information, see the following article: 

    User's mailbox is over the configured size limit in Office 365 Dedicated/ITAR

    This also applies for Litigation users who are affected because they cannot delete messages. Update the mailbox plan, verify that it's synced, and then contact Microsoft. For more information, see the following article:  

    Litigation Hold users cannot delete messages in Office 365 Dedicated

  4. If the mailbox is already set to the largest size that is available, review these options to reduce the size of the mailbox.

    • Option 1: Delete email messages that are no longer needed.

    • Option 2:  Apply an MRM policy to the mailbox. For more information, see Messaging Rights Management (MRM) in Office 365 dedicated/ITAR.

    • Option 3: Create an archive. For more information, see How to enable and disable a personal archive mailbox in Office 365 dedicated.

    • Option 4: Delete Recoverable Items immediately by following these  instructions.

      1. Set the value of the RetainDeletedItemsFor parameter on the mailbox. The RetainDeletedItemsFor parameter specifies the length of time to keep deleted items. To specify a value, enter it as a time span. The format for the time span is as follows: 


        In this format, "d" represents days, "h" represents hours, "m" represents minutes, and "s" represents seconds.

        For example, to specify the value as one week, run the following cmdlet in the Exchange Management Shell:

        Set-Mailbox – -RetainDeletedItemsFor 7:00:00:00

      2. Run the managed folder assistant for the mailbox. To do this, run the following cmdlet in the Exchange Management Shell: 

        Start-ManagedFolderAssistant –

      3. Generally, the managed folder assistant runs one time per day for all mailboxes on a server. This command submits an immediate request to process a single mailbox. Depending on the mailbox, it may take the managed folder assistant a while to process the mailbox. Wait a day before you escalate this case to Microsoft Online Service Support.

  1. Any mailbox that requires a value larger than the published limits must be reviewed, evaluated, and approved by Microsoft. Anything larger than the published limits may be considered in emergency situations only and only after the above steps have been implemented, documented, and reviewed.

In vNext, there will be an unlimited archive feature. It requires Outlook 2016 and takes 60 days to be enabled. For more information, see Enable unlimited archiving in Office 365.

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