Access OST File After Leaving: No Exchange Server Needed
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Written By
Aradhya Jain -
Approved By
Shivam Rathore -
Updated on
May 11th, 2026 - Read Time
6 minutes
User Query: I left my company recently, and my Outlook account has been disabled. I still have an OST file containing important emails and attachments, but Outlook is not opening it anymore. How can I access OST file after leaving company?
Introduction: Employees lose access to their Outlook mailboxes after leaving a company because the organization disables the Microsoft 365 account immediately. Even though the OST file still exists on the system, Outlook often refuses to open it without the original account connection. This creates problems for users who need access to important emails, attachments, contacts, or project data. In this blog, we will explain several methods to access OST file after leaving company. It includes the manual method and a professional DRS Softech OST Converter Tool for a hassle-free conversion.
What is an OST File?
OST stands for Offline Storage Table. It is an Outlook data file that stores synchronized mailbox information locally on the system. Outlook creates OST files when users configure: Microsoft Exchange Server, Microsoft 365, Outlook.com, and IMAP accounts. The main purpose of an OST file is to allow offline access to mailbox data when the internet connection is unavailable. An OST file may contain: Emails, Attachments, Contacts, Calendars, Notes, Journals, and Tasks.
OST Files Inaccessible After Leaving Job: Reasons and Solutions
Once an employee leaves an organization, the company usually:
- Disables the mailbox account.
- Removes Exchange access.
- Changes login credentials.
- Deletes the Outlook profile.
- Revokes Microsoft 365 permissions.
Because OST files remain connected to the original mailbox profile, Outlook cannot verify the account anymore. This creates an orphaned OST file, which means the data exists physically but cannot be opened normally inside Outlook.
Can You Open an OST File Directly in Outlook?
No, Outlook does not allow users to directly open orphaned OST files if the original mailbox account is unavailable. Unlike PST files, OST files are encrypted and connected to a specific Outlook profile. If the original Exchange or Microsoft 365 account is removed, Outlook usually displays errors such as:
- “Cannot open Outlook data file”.
- “OST file is in use.”
- “The file is not accessible.”
- “Cannot start Microsoft Outlook.”
Manual Methods to Access OST File After Leaving Company
When OST files become inaccessible after leaving a job, users often look for manual ways to recover important Outlook emails and attachments. Below are some commonly used methods to access OST file data after leaving a company.
Method 01: Reconnect the Original Outlook Account
- Firstly, open Microsoft Outlook.
- Configure the same Exchange or Microsoft 365 account again.
- Outlook may reconnect with the existing OST file automatically.
- Export mailbox data into PST format.
Limitations: Manually Open OST file After Leaving Company
- Requires original login credentials.
- Impossible if the account is deleted.
- Not useful for orphaned OST files.
Method 02: Access OST File After Job Change
Sometimes users can recover limited mailbox data from:
- Outlook cache
- Temporary folders
- AutoArchive PST files
However, this method is unreliable and incomplete.
Best Method to Access OST File After Leaving Company
The easiest and most reliable solution is to use a professional DRS Softech OST Converter Tool. This tool can open multiple or large OST files without requiring the original Exchange profile or Outlook account credentials. It offers a preview option to check the OST file before conversion. You can convert OST file to PST and several other formats without losing any data. It has a simple interface, which means every user can easily use it. No technical skill is required.
Simple Steps to View OST file After Leaving Company
- Download and install the DRS Softech OST Converter Tool.
- Choose “Select Files” or “Select Folder” to add your OST files.
- Preview and select the OST files to convert. Click Next.
- Then, choose Saving Formats from the given list.
- Lastly, apply advanced features and filters. Press Convert.
Advanced Features of DRS Softech OST File Converter
- It supports OST file conversion with 100% accuracy.
- Features, like preview, Remove Duplicate, Date Filter, and more.
- Option to convert the OST file into several output formats.
- Highly compatible with all Windows and Mac versions.
- Also, a free version of this tool is available to evaluate its features.
Conclusion
In this technical blog post, we explored several methods to access OST file after leaving company. Since OST files remain connected to Exchange or Microsoft 365 profiles, Outlook often blocks direct access to mailbox data. Although some manual methods may work in limited situations. Using a professional OST Converter Tool is the most practical and secure solution for opening emails, contacts, calendars, and attachments.
Frequently Asked Questions
Ans: Many users need access to old Outlook emails, attachments, contacts, calendars, invoices, and project records after leaving a company.
Ans: You can try reconnecting the original Outlook account if it is still active. However, if the account has been deleted, using the DRS Softech OST Converter Tool is the easiest way to access and convert orphaned OST files without Outlook dependency.
Ans: Yes, you can still open and recover data from the OST file using a professional OST Converter Tool. Outlook itself usually cannot open orphaned OST files once the Exchange account is deleted.
Ans: In most cases, the OST file contains synchronized mailbox data, including emails, attachments, contacts, calendars, notes, and tasks that were available in Outlook before the account was disabled.
Ans: Yes, the DRS Softech tool supports bulk OST file loading and conversion. This feature is useful for IT administrators and users managing multiple deactivated Outlook accounts simultaneously.
Ans: No, the DRS Softech OST converter tool can open OST files without requiring Microsoft Outlook installation on the system.
Ans: Yes, if you still have the OST file stored on your computer, you can recover and access mailbox data using an OST Converter Tool even if the original Exchange server is no longer available.
