Understanding Mailbox Audit Logging

Applies to: Exchange Server 2010 SP2, Exchange Server 2010 SP3

Because mailboxes can potentially contain sensitive, high business impact (HBI) information and personally identifiable information (PII), it's important that you track who logs on to the mailboxes in your organization and what actions are taken. It's especially important to track access to mailboxes by users other than the mailbox owner. These users are referred to as delegate users.

By using mailbox audit logging, you can log mailbox access by mailbox owners, administrators, and delegates (including administrators who have full mailbox access permissions). Mailboxes are considered to be accessed by an administrator only in the following scenarios:

• Discovery search is used to search a mailbox

• The New-MailboxExportRequest cmdlet is used to export a mailbox

• Microsoft Exchange Server MAPI Editor is used to access the mailbox

When you enable audit logging for a mailbox, you can specify which user actions (for example, accessing, moving, or deleting a message) should be logged for a logon type (administrator, delegate user, or owner). The audit log entries also include important information, such as the client IP address, host name, and the process or client that is used to access the mailbox. For items that are moved, the entry includes the name of the destination folder.

Contents

Mailbox Audit Logs

Enabling Mailbox Audit Logging

Searching Mailbox Audit Log Entries

Mailbox Audit Log Entries

Mailbox Audit Logs

Mailbox audit logs are generated for each mailbox that has mailbox audit logging enabled. Log entries are stored in the Audits subfolder of the audited mailbox Recoverable Items folder. This ensures that all audit logs are available from a single location, regardless of which client access method was used to access the mailbox or which server or workstation an administrator used to access the mailbox audit log. If you move a mailbox to another Mailbox server, the mailbox audit logs for that mailbox are also moved because they're located in the mailbox.

By default, mailbox audit log entries are retained in the mailbox for 90 days and then deleted. You can modify this retention period by using the AuditLogAgeLimit parameter together with the Set-Mailbox cmdlet. If a mailbox is on litigation hold, audit log entries are only retained until the audit log retention period for the mailbox is reached. To retain audit log entries longer, you have to increase the retention period by changing the value for the AuditLogAgeLimit parameter, or export audit log entries before the retention period is reached. For more information, see Create a Mailbox Audit Log Search.

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Enabling Mailbox Audit Logging

Mailbox audit logging is enabled per mailbox. Use the Set-Mailbox cmdlet to enable or disable mailbox audit logging. For details, see Enable or Disable Mailbox Audit Logging for a Mailbox.

When you enable mailbox audit logging for a mailbox, access to the mailbox and certain administrator and delegate actions are logged by default. To log actions taken by the mailbox owner, you must specify which owner actions should be audited. The following table lists the actions logged by mailbox audit logging, including the logon types for which the action is logged.

Mailbox actions logged by mailbox audit logging

* Audited by default if auditing is enabled for a mailbox. ** Entries for folder bind actions that are performed by delegates are consolidated. One log entry is generated for individual folder access within a time span of twenty-four hours. *** FolderBind and MessageBind are not logged for the default calendar.

Mailbox access by authorized automated processes, such as accounts used by third-party tools or accounts used for lawful monitoring, can create a large number of mailbox audit log entries. This may not be of interest to your organization. You can configure such accounts to bypass mailbox audit logging. For details, see Bypass a User Account From Mailbox Audit Logging.

If you no longer require certain types of mailbox actions to be audited, you should modify the mailbox's audit logging configuration to disable those actions. Existing log entries aren't purged until the configured audit log age for the mailbox is reached.

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Searching Mailbox Audit Log Entries

You can use the following methods to search mailbox audit log entries:

• Synchronously search a single mailbox   You can use the Search-MailboxAuditLog cmdlet to synchronously search mailbox audit log entries for a single mailbox. The cmdlet displays search results in the Exchange Management Shell window. For more information, see Search-MailboxAuditLog and Search the Mailbox Audit Log for a Mailbox.

• Asynchronously search one or more mailboxes   You can create a mailbox audit log search to asynchronously search mailbox audit logs for one or more mailboxes, and then have the search results sent to a specified e-mail address. The search results are sent as an XML attachment. To create the search, use the New-MailboxAuditLogSearch cmdlet. For details, see Create a Mailbox Audit Log Search.

• Use auditing reports in Exchange Control Panel   You can use the Auditing tab in Exchange Control Panel (ECP) to run auditing reports or export entries from the mailbox audit log and the administrator audit log. For details, see Auditing Tab.

Mailbox Audit Log Entries

The following table describes the fields logged in a mailbox audit logging entry.

Mailbox audit log fields

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