Help! My Mailbox Store has reached the 16GB limit!

In PSS, one of our most frequent support call generators is when a mailbox store dismounts after reaching the 16GB limit.  This 16GB limitation applies to all versions of Exchange Standard Edition.  In Exchange 2000/2003, the 16GB limit is the combined size of the .edb and .stm database files.


The good news is that a new functionality has been added to Exchange 2000 and 2003 which will temporarily increase the database size by 1GB to 17GB.  This will allow the Mailbox Store to remount, and give the Administrator a window in which to delete unnecessary database content and prepare for offline defragmentation.  In Exchange 2000 this functionality is included in the Post-Service Pack 3 Rollup.  In Exchange 2003 this is built into the product, however a registry value must be added to enable this function. 


For more detailed information on this topic, see the following Microsoft Knowledge Base article:


828070 Exchange Server Mailbox Store Does Not Mount When the Mailbox Store

Melissa Travers

Comments (4)
  1. Benjamin Mateos says:

    This is a really nice feature !

    It will save a lot of headaches to email admins.



  2. SCSI says:

    Great article – Good feature

    But why do you still have the same limit as you did back in the Exchange 5.0 days ?

  3. Ian says:

    Great Tool.

    Is there an easy way in EX55 to see if you’re running Standard or Enterprise version ?


  4. Melissa Travers says:

    Hi Ian,

    In Exchange 5.5, to determine whether you are running Enterprise or Standard Edition, you would look for certain Informational Events in your Application Log. For example these Events will be logged in Exchange 5.5 when your Information Store is started:

    Event ID: 1217

    Source: MSExchangeIS Private

    Type: Information

    Category: General

    Description: Information Store with unlimited storage capacity enabled

    If you are logging the Event ID 1217 then you are on Enterprise Edition. You will log an Event ID 1216 indicating "limited storage capacity" if you are running Standard Edition.

    In Exchange 2000, the Event IDs are the same but the verbage is slightly varied.

    Hope this helps


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