Microsoft has quietly checked off a long-standing request for its U.S. government cloud customers, marking Roadmap ID 485740 as launched. The feature—importing email from Outlook Data Files (.pst) into a mailbox in the new Outlook for Windows—is now generally available for Government Community Cloud (GCC) tenants. For IT administrators and compliance officers in federal, state, and local agencies, this isn’t just a minor update; it’s the removal of a roadblock that kept legacy email archives out of the modern, cloud-centric Outlook experience.

What exactly changed?

The Microsoft 365 roadmap entry for feature ID 485740, previously listed as “in development,” now shows a status of “launched” with a General Availability tag. The description is direct: “Outlook for Windows: Import email from Outlook Data Files (.pst) into a mailbox.” What makes this notable is the tenant scope—it’s specifically for GCC customers. The new Outlook for Windows, which began rolling out to commercial users as an opt-in toggle in 2022 and later became the default for many, has been gradually gaining feature parity with classic Outlook. But for government cloud tenants, the pace has often been slower, with security and compliance validations adding months or years to deployment timelines.

PST import itself isn’t a new concept in Microsoft 365. Commercial tenants have had several methods to ingest .pst files into Exchange Online mailboxes for years, including network upload and client-driven import tools. However, those options typically ran through classic Outlook or standalone utilities. In the new Outlook, which is built on web technologies and shares code with Outlook on the web, the client-based import path has been absent until now. This roadmap launch confirms that GCC users can finally perform the import directly within the new Outlook interface, bypassing workarounds that were often impractical in secure government environments.

Microsoft has not yet published a detailed support article specific to GCC, but the roadmap note implies that the functionality mirrors what’s available in commercial tenants. That typically includes the ability to import a single .pst file or multiple files, map them to specific mailbox folders, and preserve folder structure. However, because GCC environments may have additional restrictions on data egress and client capabilities, admins should wait for official documentation before rolling out broadly.

What it means for you

For government IT administrators

If you manage a GCC tenant, this announcement likely eases a burden that has grown heavier over the past year. As Microsoft continues pushing users toward the new Outlook—classic Outlook for Windows is not being deprecated but is clearly on a long-term maintenance track—the lack of PST import in the new client created a support headache. Users with archived emails in .pst files either had to retain classic Outlook alongside the new one, manually drag-and-drop messages, or rely on third-party tools that might not meet FedRAMP or agency-specific security requirements.

Now, you can plan a cleaner transition. Users can be instructed to import their .pst files directly into their Exchange Online mailboxes, making those messages accessible from any device via Outlook on the web, mobile, or the new desktop client. For compliance officers, this also means fewer scattered local archives that are hard to search, preserve, or place on litigation hold. Centralizing email data in the cloud reduces the risk of data loss due to hard drive failures or device theft, and it aligns with zero-trust principles that are increasingly mandated for government agencies.

However, exercise caution. The import process may still involve uploading the .pst file content to Microsoft’s servers via the client. In some GCC configurations, data pathways are tightly controlled. Confirm with your Microsoft account team or support that the import method complies with your agency’s data handling policies. Also, note that larger .pst files (typically over 10 GB) are not supported for direct client import and must be split or imported via other means, a limitation that’s consistent with commercial tenants.

For end users in government agencies

As an employee or contractor using a GCC-licensed mailbox, you’ve probably encountered the frustration of trying to open an old .pst file in the new Outlook and finding no native way to do it. You might have been told to keep using classic Outlook, switch to Outlook on the web temporarily, or—if you were technically adept—manually copy folders via a local Outlook profile. None of those are ideal.

With this feature now live, you can finally consolidate your email history. The import process, based on the commercial version, typically starts from File > Open & Export > Import/Export, or via a dedicated “Import” button in the Settings panel. You’ll select the .pst file, choose to import into your Exchange mailbox, and the messages will be uploaded and placed in their original folders. After the import completes, those emails are searchable alongside your live mailbox data, and they’ll be preserved according to your organization’s retention policies.

Be aware that importing a large .pst can consume your mailbox quota. Exchange Online GCC plans typically include 100 GB of storage, but check with your admin if you’re near the limit. Also, the import works only for .pst files, not .ost (offline cache) files, which are tied to a specific profile and cannot be imported.

How we got here

The story of PST import in the new Outlook is one of gradual feature bridging between legacy Windows code and a modern, web-first architecture. When Microsoft announced its “One Outlook” vision in 2022, aiming to unify the experience across platforms, it started from the Outlook web app codebase. That meant many classic features—COM add-ins, certain mail rule editors, and the ability to directly manipulate local files—were initially missing. PST files, being a local-file-based archive format, presented a particular challenge.

For commercial tenants, Microsoft added a basic PST import feature to new Outlook in early 2024, followed by refinements in subsequent monthly updates. But GCC tenants, hosted in separate, isolated cloud instances, frequently see features delayed by 6 to 12 months. The GCC environment must undergo additional testing and accreditation, especially for any feature that involves data movement between endpoints and cloud servers.

Roadmap ID 485740 appeared in the public roadmap in late 2024 with a target of early 2025. Its arrival signals that the feature has passed muster for government security standards. In the broader context, it’s part of Microsoft’s ongoing effort to bring new Outlook to feature parity with classic Outlook across all cloud segments. Other recent additions for GCC include third-party account support and offline capabilities, though some classic features—like public folder integration and certain advanced calendar sharing—remain in progress.

What to do now

If you’re an admin, take these steps immediately:

  1. Verify availability: Check the Microsoft 365 admin center to see if the feature has reached your specific GCC tenant. Rollouts are phased, and it may take a few weeks before all users see the import option. Look for the new Outlook build that corresponds to the GA announcement; though Microsoft hasn’t published a specific version number, the 2025-03 update channel is a likely starting point.
  2. Review documentation: Monitor the official Microsoft support article for PST import in new Outlook, which will be updated to reflect GCC guidance. As of this writing, the public support page for “Import email, contacts, and calendar from an Outlook .pst file” does not yet mention GCC or new Outlook, but expect an update shortly.
  3. Test in a sandbox: Before enabling for your entire agency, have a few power users attempt imports with test .pst files. Check for any authentication prompts, data transfer encryption, and activity logging that meets your compliance needs.
  4. Communicate with users: Draft an internal message that explains the new capability, size limits, and how to locate legacy .pst files on their workstations. Emphasize that after a successful import, the local .pst file can be archived securely or deleted, reducing clutter and security risks.
  5. Plan for classic Outlook coexistence: Until new Outlook supports all critical workflows, you’ll likely keep both clients available. But with PST import now in place, you can begin migrating users whose primary holdout was email archive access.

For end users, the action plan is simpler:

  • Update the new Outlook client to the latest build via Windows Update or the Microsoft Store. The import option will typically appear only when the feature has been lit up by your admin’s tenant configuration.
  • Locate your .pst files. They are often in Documents\Outlook Files, but if you’ve stored them on a network drive, ensure you have a local copy because network imports may not work.
  • Initiate the import and be patient. Large files can take hours to upload, and the process may run in the background. Avoid closing Outlook during the import.
  • Verify the results. After completion, check that all folders and messages appear correctly, then confirm with your admin that the emails are now in the cloud and subject to organizational policies.

Outlook: what to watch next

The launch of PST import for GCC is a piece of a larger puzzle. Microsoft’s roadmap still lists several new-Outlook features for government clouds, including full public folder support, enhanced eDiscovery integration, and the ability to add shared mailboxes from the client. As agencies modernize their endpoint environments and move away from classic Outlook, these updates will come in waves. For now, this import capability is a concrete step toward a more unified, web-powered email client that doesn’t leave legacy archives behind. IT managers should keep an eye on the Microsoft 365 roadmap for ID 484753 (new Outlook for GCC High) and ID 486295 (offline support improvements) to plan their migration timelines accordingly.