By Chas Meier and John Patzakis
In today’s compliance-driven environment, organizations must retain, discover, and manage large volumes of email data—even when the employees who once owned that data have long since departed. In Microsoft 365 (M365), this is managed through the concept of “inactive mailboxes.” An inactive mailbox is a mailbox that remains accessible for legal, regulatory, or compliance reasons, but no longer corresponds to an active user. While these preserved data stores are critical for eDiscovery, compliance, and investigations, they can pose significant challenges when it comes to efficiently locating, searching, and collecting the information they contain.
Fortunately, the latest innovations from X1 Enterprise are transforming how organizations handle these inactive mailboxes, making it easier and more streamlined than ever to discover and collect critical information—no matter where it resides.
What Are Inactive Mailboxes in M365?
Inactive mailboxes are mailboxes retained after a user leaves an organization, even after their license is removed. By placing a mailbox on legal hold or under a retention policy before deprovisioning the user, you can preserve it indefinitely without incurring licensing costs. This ensures the data remains accessible for compliance and eDiscovery. Best practices include applying holds before removing accounts, treating inactive mailboxes as part of ongoing governance efforts, and lifting holds once no longer needed.
The Process of Searching Inactive Mailboxes in Purview
In Microsoft Purview (the compliance and security center for Microsoft 365), users granted the eDiscovery manager role and each provisioned with an E5 license can search across both active and inactive mailboxes to fulfill legal or regulatory requirements. Generally, the process involves:
1. Identifying the Inactive Mailboxes: Administrators must first know which mailboxes are inactive. Inactive mailboxes do not appear in the standard active user lists and often require additional steps to locate—either through the Purview interface, the Microsoft 365 admin center, or by running PowerShell scripts.
2. Setting Up Permissions and Scope: The person performing the search needs appropriate eDiscovery roles in Purview. Once permissions are granted, they create a new content search or eDiscovery case and include the specific inactive mailboxes in the scope.
3. Applying Search Criteria: Administrators can filter the search by date, keywords, sender/recipient, or other criteria. After running the search, Purview indexes the content and returns results for review and export.
Why Users Find It Challenging
Users face significant challenges when searching inactive mailboxes due to limited visibility—these mailboxes do not appear with active ones, requiring extra effort to locate and include them. Additionally, complex eDiscovery and compliance roles can be difficult to manage, particularly in organizations with large teams or complicated approval processes. A lack of a unified interface means working across multiple portals, tools, or scripts, leading to a fragmented and easily mismanaged workflow. Finally, without an intuitive, consolidated process, adding inactive mailboxes into search scopes, running queries, and ensuring data completeness is time-consuming and more prone to errors.
As organizations scale and accumulate thousands of these mailboxes, these difficulties multiply. Managing a vast, growing inventory of inactive mailboxes transforms a cumbersome task into a formidable burden, slowing down investigations, audits, and regulatory responses, and increasing the risk of overlooking critical data.
Many organizations resort to re-hydrating inactive mailboxes by applying an active M365 license to each one (“throwing licensing”), copying all M365 mailboxes of departed employees in a separate non-Microsoft archive (“throwing archiving”), or bringing inactive mailboxes into the litigation workflow (“throwing services”) to address the problem when faced with eDiscovery requests. Each of these approaches is extremely expensive, burdensome, and fraught with risk.
Driving the Transformation of Inactive Mailboxes through New Capabilities
X1 Enterprise has long been a trusted solution for comprehensive and targeted search across M365 data sources, file servers, and endpoints. With the new release of X1 Enterprise version 5.3, X1 is taking an industry-leading step forward in how organizations manage and leverage their inactive mailboxes.
How X1 Enterprise Revolutionizes Inactive Mailbox Management:
• Unified Discovery Experience: With X1 Enterprise 5.3, legal and compliance professionals can now select inactive mailboxes directly within the platform. Instead of treating inactive mailboxes as separate or isolated repositories, X1 provides a consistent, familiar interface—just like working with active mailboxes.
• Centralized Indexing and Search: Once selected, inactive mailboxes can be staged, indexed, searched, and collected using the same intuitive workflows. This streamlines eDiscovery, ensures rapid insights, and reduces the administrative burden on IT and compliance teams.
• Seamless Integration with Microsoft Purview: X1 Enterprise automatically discovers and presents your full list of inactive mailboxes stored in Microsoft Purview (formerly Office 365 Security & Compliance Center) using only a single E5 license. This direct integration ensures that all preserved mailboxes are readily visible and actionable.
• Consistent Identification and Collection Workflows: By applying the same workflows to both active and inactive mailboxes, X1 Enterprise eliminates confusion and complexity. The result is a more efficient and effective approach to responding to legal requests, regulatory audits, and internal investigations.
Benefits of the New Approach:
1. Faster Response Times: Legal and compliance teams can rapidly identify and collect relevant information from inactive mailboxes without reinventing the wheel for each scenario.
2. Improved Efficiency: In-place indexing and targeted searching with X1 Enterprise reduces administrative overhead and streamlines processes without the need to “boil the ocean,” thereby vastly reducing licensing costs with no need for 3rd party services or archiving platforms.
3. Reduced Risk: Consistent workflows lower the chance of missing critical data or mismanaging preserved mailboxes.
4. Enhanced Transparency: Having a clear, uniform process for both active and inactive mailboxes bolsters your overall information governance framework.
In Conclusion: Embrace the Future of Inactive Mailbox Management
Inactive mailboxes are here to stay, as legal and regulatory requirements continue to mandate the preservation of key business communications. Instead of viewing these repositories as a burden, forward-thinking organizations can leverage advanced technologies like X1 Enterprise 5.3 to take control of their compliance landscape.
Ready to Learn More?
The X1 Enterprise Platform is available now from X1 and its global channel network in the cloud, on-premises, and with our services available on-demand. For a demonstration of the X1 Enterprise Platform, contact us at sales@x1.com. For more details on this innovative solution, please visit www.x1.com/solutions/x1-enterprise-platform.