Mailbox Quota in Outlook 2010 – general information and troubleshooting tips

Mailbox Size and Quota information are two different pieces of information we can get from the “Thermometer” on the Outlook status bar. The quota thermometer provides awareness of the size of your mailbox and how far you are from reaching the limit. 


Outlook reads these values from MAPI properties that are exposed by the Exchange store. The following property values exist on the store to communicate quota information (synthesized from policies in AD):

PR_MESSAGE_SIZE_EXTENDED - The current size of the mailbox (when on the mailbox root)

PR_STORAGE_QUOTA_LIMIT - Warning Threshold

PR_PROHIBIT_SEND_QUOTA - The limit where sending mail is prohibited

PR_PROHIBIT_RECEIVE_QUOTA - The limit where receiving mail is prohibited (also the maximum size of the mailbox)


These properties are visible and used via an online mode profile. In cached mode, there is a similar set of properties that are mapped to the properties listed above, so they should always reflect the same values.


PR_QUOTA_WARNING (0x341A0003) corresponds to PR_STORAGE_QUOTA_LIMIT (0x3FF50003)

PR_QUOTA_SEN D (0x341B0003) corresponds to PR_PROHIBIT_SEND_QUOTA (0x666E0003)

PR_QUOTA_RECEIVED (0x341C0003) corresponds to PR_PROHIBIT_RECEIVE_QUOTA (0x666A0003)

PR_MESSAGE_SIZE_EXTENDED (0x0E080014) has the same name but the values are retrieved from the server either directly or via the OST synchronization.


(more info on:


The total size is not computed on the fly, but updated when data is added to and deleted from the store. The free space is calculated by taking the maximum mailbox size and subtracting the current mailbox size (PR_PROHIBIT_RECIEVE_QUOTA – PR_MESSAGE_SIZE_EXTENDED).

To display quota information on the Outlook Status Bar, right-click the status bar, and then make sure that the Quota Information item is set to On. You can also view quota information by clicking the File tab of the Outlook ribbon.


For quota information to be displayed, your mailbox must be located on Microsoft Exchange Server 2007 or on Microsoft Exchange Server 2010. Additionally, you must have both of the following mailbox or store limits configured:

  • Prohibit send at
  • Prohibit send and receive at

Note : If your mailbox is located on an Exchange 2003 server, Quota Information is not displayed in Outlook 2010. Additionally, the Outlook 2010 release (RTM) version in Cached Exchange Mode does not automatically start the Mailbox Cleanup Wizard when your mailbox is full. A hotfix package that changes the Mailbox Cleanup Wizard behavior is available. After you install this hotfix, when you run Outlook 2010 in Cached Exchange Mode, the Mailbox Cleanup Wizard starts when the mailbox is full:


When you are over your warning, the Quota Information icon will show up (even if it is not enabled all the time):


Then when the user is over the Prohibit Send limit it gets more visible:


Then the Quota Information turns red


And clicking on that takes you to the File menu where you can see how far you are over your limit and how much you need to delete to be able to send again.



When can we see the quota thermometer:

The Quota thermometer is not supported on additional mailboxes, such as delegate stores. That doesn't mean we can't have a different quota for that, it’s just that we won't see it in Outlook.

If the quota on an account is unlimited or no quota set, the Thermometer will not be displayed.


The thermometer is updated and displays the information for the folder/store currently selected. It always displays account quota information for the current folder selected (except for archive or PST stores, All mail items, SharePoint folders or IMAP accounts).

The Quota Thermometer will work with multiple Exchange accounts. The thermometer will show for whichever account has focus. The same behavior applies to Exchange + another type of account.


How are the updates triggered:

Quota updates are not triggered by moving the items to a different store. All triggers are based on time or the UI (like doing a Send/Receive).  There is no UI configuration to tell the user how often we ping the server for a user-initiated update to their mailbox size.

Updates can be triggered either manually by the user or automatically


The following user actions will request the server to update the properties :

* Emptying Deleted Items

* Emptying a Folder (via the button in the ribbon’s folder tab or right-click on folder)

* Permanently deleting (shift-delete) an item

* Closing the Archive / AutoArchive dialogs


Outlook will also ping the server to update quota information in the status bar if the user is below their warning quota. These updates occur every 30 minutes. There is also an update limit that has been set in order to reduce the server load and help improve performance. In this matter there can be only one update every 3 minutes (by default).However this can be changed by the Admin through custom GPO or logon script (the policy is not available in the standard ADM template):

Path : HKCU\Software\Microsoft\Office\14.0\Outlook\StatusBar

Name : QuotaPollInterval


Value : Integer

If this value is set to 0 then the Quota Thermometer will be disabled entirely (we will never request the properties from the sever or generate any additional RPCs).


Troubleshooting guidance:

If you encounter problems with the way the quota is displayed, the main recommendation would be to have a support case with Microsoft so that a Support Engineer could assist you, depending on the particular scenario you are seeing.

However here are some things you might want to test and have the information prepared prior to doing this:

  1. Install the latest updates for the Outlook client
  2. Remove any third-party components (or try in safe mode)
  3. One critical aspect is to determine if the issue is occurring in cached mode or online mode? If available, you can also try in OWA.
  4. Check if the problem is occurring for the main mailbox or if you have additional mailboxes added in their profile, multiex or other accounts/stores for which of these stores/accounts the problem is occurring.
  5. Does it happen if you configure an Outlook profile for only one account or if you open the additional mailbox in its own profile?
  6. Get an OffCAT scan and check for any Quota related warnings/errors in the report.
  7. Check if when performing a Send/Receive action the information is correctly updated
  8. Check if after restarting Outlook the issue is still present.
  9. Check if the Antivirus is scanning the OST file and if so, please have it added to the exclusion list
  10. Check if after recreating the profile (or just renaming the ost) the issue still occurs
  11. Check the Sync Issues folder
  12. If you are using an Exchange server, verify if the following properties are set on the server:

Note: If only one or two of them are set, you need to have all three populated so you can get the accurate information.


Potential causes for quota issues in Outlook:

Normally these kind of issues are mostly seen in cache mode and can be caused by (but not limited to):

  1. Poor network or other traffic interruptions (Since the information is requested and received from the server in a low priority task, this can be truncated when something interferes with the client/server connectivity) 
  2. Information not set correctly on the server
  3. Conflicting quotas set on different stores accessed from the same profile
  4. Removing the quotas completely after the mailbox exceeded the previous quota values
  5. OST corruption
  6. 3rd party touching the OST file


Known issues and references:

  1. Mailbox Quota Information is not displayed on the Status bar in Outlook
  2. The Mailbox Cleanup Wizard does not start in Outlook 2010 when the mailbox is full
  3. Users do not receive quota warning messages after applying SP1 for Exchange 2010
Comments (4)

  1. GAR says:

    The information contained in this article is very helpful

  2. Abhay says:

    We are facing strange issue for one user only.
    User is getting quota warning intermittently. On server his mailbox is set to 1.5GB, but when he gets warning, it shows 100MB.
    Created new .ost and new outlook profile, but it couldn't resolve the issue

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