An OST file is a local copy of your mailbox that Outlook automatically creates when you connect it to an Outlook 365, Exchange, or IMAP account. It allows offline access to emails and other mailbox items. However, this file is encrypted and tied to a specific Outlook profile, meaning it cannot be directly accessed in another account or profile.
If you want to use your old OST file in a new Outlook account, you must first convert it into a PST file. This guide covers different methods to do so.
Methods to Access an Old OST File in a New Outlook Account
Since Outlook does not support direct import of OST files, you need to convert the OST file into a PST format, which can be imported into the new Outlook account.
Method 1: Use Microsoft Outlook’s Import/Export Wizard
This method only works if you can still access your old Outlook profile where the OST file was created.
Steps to Convert OST to PST Using Outlook
1️⃣ Open MS Outlook (the account where the OST file is linked).
2️⃣ Go to File > Open & Export > Import/Export.
3️⃣ In the Import and Export Wizard, select Export to a File and click Next.
4️⃣ Choose Outlook Data File (.pst) and click Next.
5️⃣ Select the folders/mailbox items you want to export and check the Include subfolders option.
6️⃣ Click Browse and choose a location to save the PST file.
7️⃣ Select Do not export duplicate items and click Finish.
After this, the OST file is now converted into a PST file and ready to be imported into your new Outlook account.
Steps to Import the PST File into a New Outlook Account
1️⃣ Open your new Outlook account and go to File > Open & Export.
2️⃣ Click on Import/Export.
3️⃣ In the Import and Export Wizard, select Import from another program or file and click Next.
4️⃣ Select Outlook Data File (.pst) and click Next.
5️⃣ Click Browse and select the converted PST file.
6️⃣ Choose Do not import duplicates and click Next.
7️⃣ Select the folders you want to import and click Finish.
This process restores your emails, contacts, and other mailbox items in the new Outlook account.
Method 2: Use OST to PST Converter Software
If the old Outlook account is deleted or inaccessible, or if the OST file is corrupted, you cannot use Method 1. In this case, use an OST to PST converter software like Stellar Converter for OST.
Steps to Convert OST to PST Using Stellar Converter for OST
1️⃣ Download and install Stellar Converter for OST.
2️⃣ Launch the software and select Choose Mailbox Manually to browse for the OST file.
3️⃣ Click Convert to start the OST file scanning process.
4️⃣ Once the scanning is complete, preview all retrieved mailbox items.
5️⃣ Click Save Converted File, select PST, and choose a destination folder.
6️⃣ Click OK to save the PST file.
Once the OST file is successfully converted, you can import the PST file into Outlook following the steps outlined in Method 1.
Conclusion
Since OST files cannot be opened directly in another Outlook account, the best solution is to convert them into PST format.
🔹 If you still have access to the original Outlook profile, use Method 1 (Import/Export Wizard).
🔹 If the OST file is orphaned, corrupted, or the original account is deleted, use Method 2 (OST to PST Converter Software).
Using the right method ensures safe recovery of emails, contacts, and other mailbox data in your new Outlook account.
