2.1.1 Ensure 'Mailbox quotas: Issue warning at' is set to ''

Information

This policy setting can automatically warn mailbox users that their mailbox is approaching its storage limit. It's suggested that this warning be set up when 90% of the mailbox size has been reached. For example, if the mailbox size is 100GB, set the warning to 90GB or 94,371,840 KB.

A value between 0 and 2,147,483,647 KB (2.1 terabytes) can be set depending on the user's mailbox size.

Rationale:

Unlimited mailbox sizes can cause the Exchange database to grow uncontrollably and consume all available disk space, potentially preventing the database from mounting properly. This can disrupt not only email services, but also other security measures that depend on timely communication.

Impact:

Users will receive a warning when their mailboxes reach the specified value.

Solution

To implement the recommended state, execute the following PowerShell cmdlet:

Set-MailboxDatabase 'Mailbox Database' -IssueWarningQuota <value>KB

OR

Perform the following actions:

Launch the EAC (Exchange Administrative Center).

Go to 'Servers' on the left and click on the 'Databases' tab.

Double-click the database and go to the 'Limits' settings.

Change Issue a warning at (GB): to <value> and click Save.

Default Value:

1.899 GB (2,039,480,320 bytes)

See Also

https://workbench.cisecurity.org/benchmarks/12442

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-6

Plugin: Windows

Control ID: c1e33441edebf3c3d871858c552ed20c2c1028c93e8b0a986be8b5dac53ac434