View OST files without Microsoft Outlook 365

After the release of Microsoft 365, I immediately purchased and installed this software bundle. I wanted to see if they implement something new to analyze *.OST files, when the MS Exchange connection is unavailable. Unfortunately, they do not have anything new, just existing options in a new package. One more thing, did I explain that I have purchased a subscription to this bundle? Microsoft does not ask for a full license fee immediately; they simply charge the client’s card monthly. And, finally, the overall payment amount is higher than a plain and simple license fee. I would agree to pay more, but I need to have a good reason to do so. Do you think, Outlook Microsoft 365 works with e-mail accounts better than its previous versions? Of course not. Does it have something new to find corrupted e-mail folders and restore them? Of course not. In this case, why should I pay more for this new package? I think I need a reliable *.OST viewer, powered by Recovery Toolbox for Outlook:

However, let us examine what they can offer now. Like previously, Microsoft does not have anything except Inbox Repair Tool to rebuild folders in Outlook Microsoft 365 and, finally, to preview folders. I use Exchange Server as my e-mail provider, so Outlook stores my e-mail in a large file of *.OST format. However, the Inbox Repair Tool cannot rebuild *.OST files at all, only *.PST files are supported. Therefore, I do not see any sense in telling you about this tool. Let us conclude that Microsoft is unable to access *.OST files when Outlook is absent, for preview, and there is not any chance to recover such files, if necessary. You may ask if there are other ways and methods? Sure, but they require programs, developed by other companies, independently from Microsoft. If you insist on using Inbox Repair Tool because you admire this tool, for example, you need Recovery Toolbox for Outlook to convert data from *.OST to *.PST. When done, you could use Inbox Repair Tool to recover data and look inside corrupted folders. Yes, you can, but why? Recovery Toolbox for Outlook can do everything; other tools are no longer needed.

How to Use Free OST Viewer

That’s easy; the app works offline under any version of MS Windows. What if Outlook Microsoft 365 has suddenly stopped working and Exchange mailbox becomes inaccessible? You need precisely this tool to access data from *.OST files offline and view your Exchange mailbox. This option is free unless you need to rebuild e-mail and compose a clean and trouble-free file that connects to Outlook Microsoft 365. Maybe you simply need to take a brief look into your old mailbox and write down some notes. It should be enough to restore everything. It costs nothing to get the setup file of Recovery Toolbox for Outlook from the developer’s website and install it on any computer, maybe an offline PC for security reasons? Feel free to decide yourself. The OST viewer should be applied as follows:

  1. Get the installer of *.OST Viewer from here:
  2. Deploy it on any hardware (PC or laptop), working on Windows
  3. Open this tool and select an *.OST file to preview
  4. Begin the processing of mailbox in question, check if it finishes without issues
  5. Look through the contents of *.OST file, rebuilt by *.OST Viewer
  6. Convert restored data into a mailbox of *.PST format

Note the last step is not available until you activate Recovery Toolbox for Outlook. Decide if you need it, or not? Say, you just want to see some forgotten contacts and critical notes. In this case, it is free; its registration is not needed. Otherwise, if you are going to rebuild your existing mailbox, register the free OST Viewer to remove all limitations. After this, you can convert data into a clean and openable file of *.PST format. Remember, this option works on Windows only, no exceptions, but what should you do when there is a need to open an *.OST file from another device that does not use Windows?

Free Online OST Viewer

This service allows processing *.OST files anywhere: from an Android tablet, iOS, anything. Those who want to view *.OST files, should upload their mailboxes to remote service and pay. In the very end, they get undamaged files of *.PST format, openable in any compatible e-mail client, Outlook Microsoft 365, for example. Indeed, it is not entirely free. However, its cost is cheaper than a permanent license for Recovery Toolbox for Outlook. Here are the online service guidelines:

  1. Open this link:
  2. Select a local OST file to upload
  3. Enter either an e-mail address or CAPTCHA
  4. Make a payment to the service and download results

These steps should not be complicated even for new users. However, to rebuild your e-mail, you should pay a one-time fee, I hope the sum is not too large for anyone. In case of doubts, try to find a Windows computer and view OST file locally, it costs nothing after the local deployment of the app.


After the release of Microsoft 365, they should provide something new. After all, they get more and more money, but they do not offer anything more. That’s the problem. Since Microsoft does not provide information on how to view OST file without Outlook, you count on other developers only. Fortunately, Recovery Toolbox for Outlook has a reliable solution: users can apply it to see *.OST files independently from any e-mail software. The software registration fee is taken for additional options only, so if you need to repair/convert data, please buy a license and register the program. Without these other options, it is free; the usage of the toolis not limited in time. When accessing *.OST files, this app does not change them, so the app developer assures, the safety of its toolis guaranteed.

Hope you enjoy this tool, and it is beneficial for you and your colleagues to open *.OST files and see their contents.


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