But knowing the process on how slow my local state government takes to fix things, it could be a long time. They took 4 months to fix a crosswalk light post after some idiot crashed into it and I couldn't walk anywhere without taking a huge detour. Large mailbox sizes, unstable network connections, and abrupt shutdowns are the leading causes of OST corruption. Microsoft provides a built-in tool called SCANPST.EXE to scan and repair minor OST corruption.

Repair Outlook OST File Not Working in Office 365 – Complete Fix (

If your Outlook OST file isn’t syncing properly with Office 365, you’re not alone. Thousands of users face corrupted OST files, sync errors, and missing mailbox data after system updates or unexpected shutdowns. In this 2025 guide, we’ll show you how to repair the Outlook OST file and restore seamless email performance without losing important data.

Fix Outlook Stuck on Synchronizing Subscribed Folders (2025 Guide)

A corrupted OST file can pause your business communication, but with these repair steps you can restore your Outlook in minutes. Follow each method carefully, keep your account synced to Office 365, and maintain regular backups to avoid future data loss. You’ll see files ending with ".ost" — these store Outlook data file cannot be accessed your cached mailbox data.

Step 5: Run Outlook in Safe Mode to Check Add-Ins

• Microsoft provides a built-in tool called SCANPST.EXE to scan and repair minor OST corruption.
• Follow each method carefully, keep your account synced to Office 365, and maintain regular backups to avoid future data loss.
• Large mailbox sizes, unstable network connections, and abrupt shutdowns are the leading causes of OST corruption.
• This is the break room/lounge for USPS employees; USPS does not maintain a customer service account for this sub, you can use other social media contacts or simply visit your local post office for assistance.
• If your Outlook OST file isn’t syncing properly with Office 365, you’re not alone.
• Worst nightmare for paying Bills and Trading Card Sellers like me since the out letter slot is unavailable too, so I have to go to the post office as well to send out letters.

Yes — Outlook will re-sync mailbox data from the server once you relaunch the app, as long as you use an Exchange or Office 365 account. Worst nightmare for paying Bills and Trading Card Sellers like me since the out letter slot is unavailable too, so I have to go to the post office as well to send out letters. It's been like this for 4 weeks and USPS told us at the start the "problem will be fixed soon wait 3 weeks" 3 weeks have passed. This is the break room/lounge for USPS employees; USPS does not maintain Outlook OST vs PST repair a customer service account for this sub, you can use other social media contacts or simply visit your local post office for assistance.

Prevent Future OST Corruption

Yes ✅ You can connect with our experts on WhatsApp for quick remote support and step-by-step troubleshooting guidance. If you’d like to learn more about mailbox repair, check out our in-depth interview with Grant Wallace. Navigate to Send/Receive → Work Offline and toggle it. If Outlook reconnects successfully, the OST issue was likely caused by temporary disconnection from Office 365 servers. If the OST works properly, repair corrupted OST in Outlook disable unnecessary add-ins from File → Options → Add-ins.