Exchange Server 2000/2003 allows the Exchange Administrator to set limits on the mailboxes of users in the Exchange Organization (read Setting Mailbox Limits, Working with Store Policies and Overwriting Setting limits on the mailboxes help control the database size and plan for efficient backup, restore and maintenance tasks.
However, in most scenarios, there will always be users that think that they deserve more storage space than they were given in the first place. Some of these are VIPs, others just need it for their work, and the rest are simply trying to make their life easier.
So, whatever may be the reason, you might find yourself in need to configure higher mailbox limits for some users.
Well, up to this point all I did was to explain what you already know. However, there is one tricky bit:
When trying to configure mailbox limits higher than 2097151 KB the Exchange System Manager (ESM) or Active Directory Users and Computers (ADUC) snap-ins will not allow you to enter these higher limits.
You will receive an error saying: “The value for ‘Issue warning at (KB)’ is not valid. Specify a value from 0 through 2097151”.
The mailbox limits are actually Active Directory attributes. If you set a sample user’s mailbox limits and look at the user object with a tool such as LDP or Adsiedit.msc you will notice that they are:
Issue Warning = MDBStorageQuota
Prohibit Send = MDBOverQuotaLimit
Prohibit Send and Receive = MDBOverHardQuotaLimit
These limits are part of the UI, and NOT a hard coded limit on the attribute itself.