Using Adsiedit to Increase User Mailbox Size Beyond 2GB on Exchange Server 2003

If you use Exchange 2003 (I’m not sure if the same applies to later versions), you may have noticed that you cannot set a user’s mailbox size to anything greater than 2097151KB (2GB).

The good news is that this limit is only GUI imposed (soft limit) and not a hard value fixed on the exchange server software it self (hard limit).

Increasing a user’s mailbox is really easy and safe – however, I don’t recommend that you configure the size to some unreasonable or extreme limit.
As always, a full backup of the mail store is recommended before changing any settings on the Exchange.


  1. Go to Start –> Run
  2. Type adsiedit.msc
  3. Go to the container which contains your users
  4. Right click the user you want to increase the mailbox size for and select Properties
  5. Edit the values mDBStorageQuota, mDBOverQuotaLimit, mDBOverHardQuotaLimit and mDBUseDefaults

mDBStorageQuota is the value (in KB) in which you want to issue a warning.
mDBOverQuotaLimit is the value (in KB) in which you want to prohibit sending of mail.
mDBOverHardQuotaLimit is the value (in KB) in which you want to prohibit sending and receiving of mail.
mDBUseDefaults (boolean) decides whether the default settings should be used or not. You should set this to False if you have configured the above values and want to use them.

That’s it! The user should now be configured with the new mailbox size.


4 thoughts on “Using Adsiedit to Increase User Mailbox Size Beyond 2GB on Exchange Server 2003”

  1. Very cool, I just happened to stumble upon this. I am learning sbs/exchange2003 now and thought this was rather relavent. I was surprised to see a more recent post on this topic. What Service Pack level are you running on exchange 2003?


    1. Hi Mac,
      I’m glad you found the article relevant to your work 🙂
      We are running SBS 2003 with SP2.
      Hope that helps.

  2. Have you tried installing activesync on the SBS server? I’m about to try it.. I’m thinking that the SBS server should be protected with an ISA server on the front end of it….Everyone HAS to have their iphones working with corporate email…

    1. ActiveSync was already installed when I joined the company I work for. Although, from what I have heard, some hackery/tweaks needed to be performed to get e-mail working on iPhone devices. I suggest setting up AS on your systems (with SBS SP2) and seeing if you have the same problem.
      We don’t use an ISA server (had to Google it to find out what it was :)) – an employee is able to access their OWA from any browser over https… a VPN session is needed if they want to access the ‘real’ Outlook client from their desktops.

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