Receiving Duplicate Emails in Outlook – How to solve a corrupt PST file

Duplicate emails in Outlook can cause a variety of problems for the user. Not including the general annoyance of when emails are continuously doubling in the user’s inbox, duplicate emails serve to slow down the overall performance of the device operated by the user, due to their sheer volume. 

Duplicates can be caused by many things, such as file corruption and/or an error in synchronizing Outlook with another device, to name a couple. Often though, the user struggles to find the source.

One of the most common causes for duplicate emails, however, is when Outlook encounters a corrupt PST. A fundamental aspect of Microsoft’s operations, PST corruptions are one of the main causes of duplicate emails, due to how much they register and, conversely, how much they lose if and when they become corrupted.

As such, this blog will focus on the ways in which PST’s can become corrupt. This is due to the fact that PST corruption is one of the leading causes of duplicate emails. Therefore, the article will detail what can cause PST corruption, and how these issues can be averted. In turn, keeping your PST’s well managed will reduce the risk of duplicate emails, or if you’re currently affected by them, at least one of these steps should serve to alleviate you of them.


  • What is a PST?
  • Hardware Problems
  • Software Problems
  • How can these issues be resolved?

What is a PST?

PST stands for ‘Personal Storage Table’. They are defined as personal information storage files, and they are something used within Microsoft systems that stores copies of things such as calendars, messages, and other aspects of the Microsoft software. 

These Outlook files have a file size limit of 2GB. If ever this figure is exceeded, it can contribute to PST corruption. Before delving into any potential problems that may be causing your duplicate emails, it may be worth seeing if your PST file size has been broken.

Any malfunctions within the PST can be classified as one of two subsections, hardware, or software. Malfunctions within either the hardware or the software can be leading contributors to PST corruption.

PST corruption can be caused by a plethora of things. Hardware issues can include:

  • Complete power failure when transferring.
  • Hard disk (device) failure can affect PST’s if they happen to be stored on a corrupt aspect of the disk.
  • If a network device becomes damaged, then PST’s can become affected if they happen to be stored on that network.

PST issues are not exclusive to hardware however, as software can just as equally impact a PST and cause corruption:

  • Viruses
  • Oversized PST files
  • Improper shutdown of the system.

How to fix duplicate emails in Outlook

Well, there are several resolutions to the aforementioned issues. For example, to solve and/or prevent power failure, you could look to buy an uninterruptible power supply, or a UPS. Of course, this isn’t the most widely applicable solution, nor is it one that everyone would be able to afford.

Generally though, there is a system that you would be able to install in order to resolve any PST issues you may have. Microsoft offers a free inbox repair tool, also known as scanpst.exe, with its overarching aim being to assist the user with any problems they are having with their PST’s.

More often than not, scanpst.exe lets you scan a file, before allowing you to recover any repaired items through Outlook. It allows you to make a file for your new .pst’s from then on, whilst also giving you the option to recover repaired items from your backup file.

To open scanpst.exe on your computer, you will first need to make sure your computer is showing hidden files. Below is a breakdown on how to, first, show hidden files and, second, how to access and run scanpst.exe.

First, click the Windows icon in the bottom left of your screen. From here, scroll down until you find the file titled Windows System, which has been emphasised by the green circle. Click this, and then click File Reporter, which is highlighted below via the red rectangle.

Once you have opened file explorer, you should look to the top bar and find the View tab which, should you need it, has been highlighted in the screenshot below. Open the View tab.

After clicking on the View tab, a small dropdown menu should appear. At the very end of this, to the right, is an Options box. Open that.

When you have opened this option box, you will be greeted with a menu. Navigate to the View tab, from which you’ll be greeted with what you see below. Highlighted is the section regarding hidden files. As a default, it will choose to not show hidden files. Once you select the show hidden files option, you will be able to find scanpst.exe.

From here, you should be able to search for scanpst.exe manually. If this isn’t the case for you however, don’t worry. If you can’t find it manually, you will want to open Task Manager.

In case you’re unsure on how to open this, below is a small walkthrough on how to do it.

Simply search ‘Task Manager’ in the search bar at the bottom of your screen. Click it when it appears. Before you do this though, make sure you have the Outlook application open.

Now, if you made sure you had the Outlook application open prior to opening Task Manager, you should see it at the top of your Manager menu. Right click Outlook, and select open file location.

You will be greeted with a very long list. As you’ve just opened it, Outlook will be highlighted. It should look something like this:

Scroll down this list until you find SCANPST, which will look like this (it has been highlighted in red):

When you have open scanpst.exe, you will be greeted with a menu. From here, unless you know the specific name, click Browse in order to search through your PST’s in order to find which one is corrupted.

Often, the file you’re looking for will be in one of these locations:

  • drive:\Users\<username>\AppData\Local\Microsoft\Outlook
  • drive:\Users\<username>\Roaming\Local\Microsoft\Outlook
  • drive:\Users\<username>\Documents\Outlook Files
  • drive:\Users\<username>\My Documents\Outlook Files
  • drive:\Documents and Settings\<username>\Local Settings\Application Data\Microsoft\Outlook

Once you’ve found your file, enter it and click Start to start the repair process. The tool will scan through your file(s) and notify you if it detects any errors. If it does, click Repair

It’s worth noting that one run through of scanpst.exe doesn’t guarantee either your files safety, nor their recovery. You may have to run the program several times, but it’s better you do this than have your files remain corrupted.

I hope you enjoyed this blog. In it, we ran through what a PST was, what can cause them, and the best way to fix them that is scanpst.exe. I hope it was as helpful as you wanted it to be. As always, if you have any feedback or issues, please feel free to get in touch with our team.

Thanks for taking the time to read this blog, I hope you found it as helpful as you hoped it would be! If you have any issues, please don’t hesitate to contact us.

Michael Fontana

Michael Fontana has been the managing director of telecoms and MSP Optionbox for over a decade and has worked in various telecommunication roles over the last 20 years. Michael has been involved in many exciting projects, such as co-founding telecoms and IT businesses and has now built up a team of more than 15 staff, serving over 300 clients nationwide. With a wealth of experience in IT and a passion for technology, Michael is now helping BTP to produce the highest quality guides on the internet. You can connect with Michael on LinkedIn.

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