Network Administration: Mailbox Storage Limits

Exchange Server 2010 lets you set a limit on the size of each user’s mailbox. In a very small organization, you can probably get away without imposing strict mailbox size limits. But if your organization has 20 or more, you need to limit the size of each user’s mailbox to prevent the Exchange private mail store from getting out of hand.

Exchange provides three kinds of storage limits for user mailboxes:

  • Issue warning at: When this limit is exceeded, an e-mail warning is sent to the user to let them know that their mailbox is getting large.

  • Prohibit send at: When this limit is reached, the user can’t send e-mail, but the mailbox continues to receive e-mail. The user won’t be able to send e-mails again until he or she deletes enough e-mails to reduce the mailbox size below the limit.

  • Prohibit send and receive at: When this limit is reached, the mailbox shuts down and can neither send nor receive e-mails.

You can (and should) set a default storage limit that applies to all mailboxes in your organization. You can also override these limits for specific users.

To configure the default storage limits for all mailboxes, follow these steps:

  1. Choose Start→Administrative Tools→Microsoft Exchange Server 2010→Exchange Management Console.

    This fires up the Exchange Management Console.

  2. In the Navigation pane, navigate to Microsoft Exchange→Microsoft Exchange On-Premises→Organization Configuration→Mailbox.

    This displays the organization’s mailbox configuration.

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  3. In the list of mailbox databases, right-click the mailbox database and choose Properties.

    Usually there’s only one mailbox database listed; the mailbox database is highlighted in the figure.

    When you choose Properties, the Mailbox Database Properties dialog box is displayed.

  4. Click the Limits tab.

    The Limits tab is displayed.

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  5. Change the storage limit settings to meet your needs.

    By default, the storage limits are set quite high: Warnings are issued at about 1.9GB, send permission is revoked at 2GB, and both send and receive permissions are revoked at about 2.3GB. A 2GB allowance for each user’s mailbox is generous, but bear in mind that if you have 100 users, that means your mailbox database may grow to 200GB. You may want to set lower limits.

  6. Click OK.

    The limits you have set take effect immediately.

If you impose restrictive default storage limits for your users, you may want to relax the limits on a case-by-case basis. For example, some users may require a larger mailbox because of the type of work they do. And you probably don’t want to impose a tight limit on your boss.

Fortunately, it’s easy to override the default limits for a specific user. Here are the steps:

  1. In Exchange Management Console, navigate to Microsoft Exchange→Microsoft Exchange On-Premises→Recipient Configuration→Mailbox.

  2. Right-click the user for whom you want to override the limits.

    This summons the Mailbox Properties dialog box.

  3. Click the Mailbox Settings tab.

  4. Double-click Storage Quotas.

    The Storage Quotas dialog box appears.

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  5. Deselect the Use Mailbox Database Defaults check box.

    This enables the controls that let you set the Issue Warning, Prohibit Send, and Prohibit Send and Receive limits.

  6. Set the appropriate limits for the user.

  7. Click OK.

    The storage limits are configured.