What is an NST File and How to Open NST File in Outlook?

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  • Published on
    August 8th, 2019
  • Updated on
    December 22, 2021
  • Read Time
    4 minutes
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If you are an Outlook user then I am quite sure you must be aware of OST and PST file formats but fewer users know about NST file format of MS Outlook. They have only one question in their mind that What is an NST file format? Well, in this blog I’ll tell you about NST file and where are they located. I would be also covering the creation of an NST file and how to open NST file in Outlook.

What is Office 365 NST File?

NST is basically an extension of Outlook file which is stored on the local machine whenever a user configures Office 365 in Outlook. MS Outlook Synchronizes the local copy of Office 365 and stores it on the PC in a group storage table also known as GST files. The reason for creating the GST file is to allow the user to work in an offline mode on Office 365 as OST works for MS Outlook. In order to clear your facts, both these files OST and GST are stored in the same folder.

Outlook Slider manages and controls the data synchronized in the GST file with .nst extension. The NST files usually stores conversations in groups and calendars whereas the OST file stores mailbox items and other folders into it. Whenever a user accesses IBM Lotus Notes using Outlook Connector then it creates NST files on the local machine.

How to Create the NST File?

The NST files are created automatically whenever you configure Office 365 to Outlook because all the cached data of Office 365 is stored in NST file format.

Steps to Create an NST file

  • Open MS Outlook and Add your Office 365 account into it.
  • The adding process will start displaying a message we’re getting things ready.
  • Now, enter the Password of your Office 365 account and click on OK Button.
  • Mail Delivery Location Dialogue box will appear in which you have to click on OK to continue.
  • You’ll receive a Confirmation Account Setup is complete and click on OK button.
  • Once you click on OK button, MS Outlook will start configuring emails of Office 365 into the same account and the whole duration depends on the size of your database.
  • After the completion of the whole process, you can view see NST files on the same location where OST files are saved.

Find the Location of NST file

  • Make a Right-Click on the Office 365 Account and then Select Data Files Properties.
  • Under the General Tab Click on Advanced Button.
  • Click on Outlook Data File Setting under the Advanced tab in the new wizard.
  • From the File Box copy the whole location into the clipboard.
  • Now, open Windows Explorer and paste the copied location till “Outlook” only.
  • Now, you can see the NST file at the same location which you have pasted.

How to Open NST File in Outlook?

As I have told you earlier that NST files are the cached offline files of Office 365 and therefore they are always in an unreadable form. In order to view NST files in Outlook, you need to convert it into PST and then import PST file in Outlook.

Convert NST to PST and Open into Outlook

  • Locate the NST file in your PC.
  • Make a Right-Click on it and then select Properties.
  • Under the General tab Change the file extension from .nst to .ost.
  • Once you change the File name, open Sysinfo OST to PST Converter.
  • Add OST file into the software which you have renamed.
  • All the data will be previewed to you in a readable form.
  • Select the files and folders which you want to save and click on the Save button.

Once you save the OST file as PST, you can import it into your Outlook account and ultimately open NST file in Outlook without losing a single data.


Now, you know that there is one more file format of MS Outlook known as NST file format. OST and PST are known to file formats but very few people are aware of NST file format. I hope you have got the answer to your question that what is an NST file format and How to Open NST File in Outlook. You have also learned how to Create and locate the NST file. If one wants to open NST file in Outlook then he can do so with the help of simple steps. I hope you gained sound knowledge about NST file from this article.

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