Microsoft has started rolling out read‑only access to contacts stored in Outlook Data Files (.pst) for Government Community Cloud (GCC) customers using the new Outlook for Windows. The feature, tracked under Microsoft 365 roadmap ID 485756, lets federal, state, and local agency workers view legacy address books without importing data—a move that closes one of the last remaining gaps for government organizations migrating away from classic Outlook.
What’s changing
The update enables the new Outlook client to open .pst files and display the contacts folder in a read‑only view. Until now, government users who relied on the new Outlook could access only email messages from .pst files; contact records were invisible unless you fired up the classic Outlook desktop app or manually imported the data into the cloud mailbox.
Here are the specifics:
- In‑app experience: After enabling PST support in Outlook’s settings, you can open a .pst file directly from the navigation pane. The contacts folder appears under the file name, and clicking it shows all entries in a familiar, read‑only card view.
- No write capability: You can copy contact details, start a new email from a contact card, or export the list, but you cannot edit, delete, or add anything to the .pst file from inside the new Outlook.
- Search works across PSTs: Once a .pst file is attached, its contacts become searchable through the top‑level search box, though results are siloed by data source.
- Requirements: The feature is available only in the new Outlook for Windows (version 1.2024.508.100 or later, Microsoft 365 subscription required) and must be turned on manually via Settings → General → Data Files → “Open Outlook Data File (.pst) support”.
Microsoft’s roadmap entry for 485756 marks the feature as “General Availability,” meaning it is fully supported for production use in GCC environments. The rollout began in late March 2025 and should reach all GCC tenants within four to six weeks.
What it means for you
For frontline workers and information managers
If your agency still keeps historical contacts in .pst archives—common in law enforcement, public health, or regulatory roles that maintain long‑term stakeholder records—you no longer have to toggle between two Outlook versions. Every contact that was previously locked inside a legacy file is now just a search away inside the modern interface.
For IT administrators
- Simplifies migration: Agencies can move users to the new Outlook sooner, even if some team members still rely on old .pst files—provided the files only need to be read. You won’t have to schedule costly .pst import projects for contacts that are rarely updated.
- Reduces classic Outlook dependency: This weakens one of the last arguments for keeping classic Outlook installed on government endpoints, which in turn shrinks the attack surface and lightens software management.
- Compliance benefit: Because the .pst data remains in its original file—encrypted and stored on the local drive or a network share—the chain of custody for records stays intact. Read‑only mode ensures no accidental modification during an e‑discovery process.
- Still no calendar support: The roadmap entry covers contacts only. Calendar items, tasks, and notes inside .pst files remain inaccessible in the new Outlook for GCC. Teams that need to browse old calendar entries must still open the file in classic Outlook or use a third‑party viewer.
For developers and ISVs
Government‑focused independent software vendors that integrate with Outlook contact data can now build solutions that assume .pst contact visibility is consistent across both commercial and GCC clouds. The read‑only MAPI interface exposed by the new Outlook will let line‑of‑business apps pull legacy contact lists without calling the classic Outlook API.
How we got here
PST files are a relic of on‑premises Exchange. For decades, they served as the offline container for emails, contacts, calendars, and more. When Microsoft launched the “One Outlook” project (now simply the new Outlook) in 2023, PST support was missing entirely—a deliberate choice to nudge users toward cloud‑first storage. The outcry from enterprises and government customers forced a rethink.
A brief timeline:
| Phase | Date (approx.) | What shipped |
|---|---|---|
| Email read‑only (commercial) | March 2024 | New Outlook could open .pst files and show mail folders, read‑only. |
| Contacts and calendar preview (commercial) | July 2024 | A toggle appeared in the Settings menu to enable contacts and calendar browsing inside .pst files; Microsoft warned of rough edges. |
| Contacts generally available (commercial) | November 2024 | Roadmap ID 95680 closed; commercial customers got read‑only .pst contacts as a standard feature. |
| GCC rollout begins | Late March 2025 | Roadmap 485756 reached GA, bringing the same read‑only contacts feature to Government Community Cloud tenants. |
GCC environments typically trail commercial cloud releases by six to twelve months because of additional compliance testing—FedRAMP, CJIS, IRS 1075, and others. The lag here, roughly four to five months after the commercial GA, is consistent with past feature deliveries.
What to do now
Turn on .pst contact access
- In the new Outlook, select Settings (gear icon) → General → Data files.
- Enable the toggle “Open Outlook Data File (.pst) support”.
- If the toggle is missing, make sure Outlook is updated to the latest version (File → Office Account → Update Options → Update Now) and that you’re using a Microsoft 365 account.
- Once enabled, return to the navigation pane, right‑click “Add shared folder or mailbox”, then choose “Open Outlook Data File (.pst)”.
- Browse to the .pst file and open it. The contacts folder will appear as a sub‑node.
What to do with read‑only contacts
- Copy to a cloud folder if you need to edit or sync them: select all contacts (Ctrl+A), hit Ctrl+C, navigate to a contact folder under your Exchange mailbox, and paste.
- Export as a CSV from another application if you need structured data: classic Outlook’s Import/Export wizard still works on the same .pst file.
- Set expectations with users: Make sure they know the .pst contact list won’t update when they modify a cached entry in their cloud address book. Write a one‑page quick‑start guide for your help desk.
If you still need calendar or write access
Keep a copy of classic Outlook available, or plan a migration project that imports .pst data into Exchange Online mailboxes using the Microsoft 365 Import Service. For most government organizations, the import path is the ultimate answer; this read‑only stopgap buys you time.
What comes next
Roadmap 485756 solves the contacts headache, but Microsoft has not signaled when .pst calendar support will land for GCC. The commercial cloud roadmap item for read‑only .pst calendars (ID 113855) is currently in development and likely to reach GA for commercial users in mid‑2025; GCC customers can expect a similar months‑long delay thereafter.
More broadly, this release shows that Microsoft remains committed to making the new Outlook viable for government even while it phases out the classic client. With contacts now available, the navigation parity between classic and new Outlook is nearly complete for the PST use case. The remaining gaps—calendar, tasks, and notes—are small but significant for agencies that rely on .pst archives as chronological records repositories. Watch for updates on those roadmap items, and start talking to your Microsoft account team about piloting a .pst‑free future today.