Setting Limits on Databases

After you create a database, you can customize the maximum storage limits and deletion settings for mailboxes stored on that database. Although some organizations consider placing limits of any kind on mailboxes to be draconian, most understand that preventing users from storing unlimited amounts of archaic data and enforcing the regular automatic purging of deleted items helps to ensure a healthy and happy messaging system that benefits the entire organization.

By default, these settings apply to all user mailboxes stored on that database. However, specific limits on individual mailboxes can be configured to override these database-wide settings. This can be useful when you want to set a limit for all users on a particular database, but you have one user who needs more (or less) restrictive settings. To configure these options, perform the following tasks:

1. Start the Exchange Management Console.
2. In the Console Tree, navigate to the Organization Configuration and select the Mailbox node.
3. In the results pane, select the database you want to configure.
4. In the action pane, click Properties to open the database properties sheet. Note: There are two properties options in the action pane. One for the database, co-located with Dismount Database and Move Database Path, enables you to configure the properties of the object. The other is associated with the database copy and offers general information about the database copy such as the server status, latest available log time, and other information. For our purposes, we select the former.
   Alternatively, you can simply locate the database you want to modify and doubleclick it in the results pane.
5. Select the Limits tab.
6. Several limits are available to configure for the database. You can configure any of the following settings on the database:
   • Storage Limits-The storage limits section enables you to configure restrictions on all mailboxes located within that database. The available storage limits options are as follows:
     • Issue warning at-1,991,680KB (1,945MB or approximately 1.9GB). This is not a "hard" limit, but a warning threshold. When this limit has been exceeded, the user will get a message warning them.
     • Prohibit send at-2,097,152 KB (2,048 MB or 2 GB). This is a "hard" limit. When a mailbox exceeds this threshold, the user is unable to send mail. This does not impact the user's ability to receive mail, ensuring the user does not miss any messages while scurrying to clean up their mailbox.
     • Prohibit send and receive at-2,411,520 KB (2,355MB or approximately 2.3GB). This is also a "hard" limit. When the mailbox exceeds this limit, the user can no longer send or receive messages. Incoming mail destined for this mailbox will be returned to the sender.
   • Warning Message Interval-By default, storage limit warning messages are sent daily at 1:00 a.m. This selection can be customized to perform the warning at a different time of the day, or even to send multiple messages at various times of the day. Click Customize to change the default setting.
   • Deletion Settings-The deletion settings dictate how deleted items and mailboxes in the database will be dealt with. The available deletion settings options are as follows:
     • Keep Deleted Items for (Days)-By default, mailbox databases are configured to keep deleted items for 14 days.

       Note: There is often some user confusion as to what messages can be recovered using the Tools, Recover Deleted Items option in Outlook. There are two types of deletion: Hard (or physical) deletion and Soft (or logical) deletion. When users delete an item, it goes to their Deleted Items folder and can be recovered simply by dragging and dropping it back into their Inbox. If users go to the Deleted Items folder, and again delete the message, or if they select Tools, Empty Deleted Items Folder, the item has been soft deleted and can be recovered using the Tools, Recover Deleted Items option. This recovery can be accomplished if it is initiated within the window set in the Keep Deleted Items for (Days) section field. However, if a user enters the Recover Deleted Items utility and selects to purge a message, or if the Keep Deleted Items for (Days) period has expired, the item is hard deleted and cannot be recovered without resorting to backup/restore methods.

     • Keep Deleted Mailboxes for (Days)-In Exchange Server 2010, as it was in Exchange Server 2007, deleting a mailbox does not mean that it is permanently purged from the database immediately. The mailbox is flagged for deletion and can no longer be accessed by users. After the mailbox retention period controlled by this setting has been reached, the mailbox is then purged from the system. This option is extremely useful if a user deletion occurs that is the result of a mistake and enables the administrator to recreate the user object and reconnect the deleted mailbox. By default, this setting is set to 30 days. It can be configured anywhere from 0 (immediate purge upon deletion) to 24,855 days. It is unlikely you will ever need the upper limit (equivalent to a little more than 68 years), but this setting can be adjusted to meet your organization's needs. Unless disk space becomes an issue, it is recommended that you do not disable the deleted mailbox retention feature.
     • Don't permanently delete items until the database has been backed up-This final setting is not enabled by default. By checking this option, you instruct Exchange Server to not delete items or mailboxes, even after the retention period has expired, until the database has been successfully backed up. By selecting this option, you ensure that you can recover critical items or mailboxes from backup tape, even after the purge has been completed.