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How to Import OST into Office 365 (Exchange Online)

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By: Praveen Dixit

June 22, 2018

Here, we will talk about how to import OST files into the Office 365 cloud platform. I discuss two different methods for migrating OST to Exchange Online (Office 365). If you are planning to switch to Office 365, then this blog will surely help you.

How Can We Migrate OST Files to Office 365 Cloud Mailbox?

There are no direct methods to migrate OST files to Office 365. But if you still want to know the process of importing OST files into Office 365, then you need to convert OST files to PST format. After that, you can manually import PST files into Office 365 using the Microsoft Network upload method. And you can also use a third-party tool for uploading OST files directly into the Office 365 cloud platform. There are many third-party solutions; MailsDaddy OST to Office 365 Migration Tool is one of them. It will help to save OST files into an Exchange Online account, along with all items like emails, attachments, tasks, appointments, meetings, contacts, notes, etc.

Here, I am going to explain two methods of importing OST files into Office 365. So read both methods and choose a suitable one for your migration.

Method 1: After Converting OST Files to PST Format, Upload to Office 365

It is the indirect method to import OST files into Office 365. First, convert the OST files to PST format. After that, you need to upload the PST files to Office 365.

Step 1: Convert OST files to PST format

  • Open your Outlook account >> file >> import and export.
  • Select Export to a file and click on Next.
  • Then go to Personal Folder File (.pst) >> Next.
  • Now select email or folder; check on Include Subfolder >> Next.
  • Browse the location where you want to save the file and check “Replace duplicate with items imported” and click Next.
  • Put the password (if you want, otherwise skip it) and hit Ok.

Note: If the Exchange server is offline or you are not connected to the server, then this time given method will not work. In that case, simply use the OST to PST converter tool for converting OST files into PST format.

Step 2: Migrate PST files to the Office 365 Cloud Platform

  1. Login to your Office 365 account >> Admin Center >> Exchange.
  2. The Exchange Admin Center window will appear>> Permission>> double click on Organization. Management a new popup appears >> + sign >> select Mailbox Import Export >> Add >>Ok.
  3. After that, select Mailbox import export again >> Save.
  4. Now, go to Admin Center >> Setup >>Data Migration >> click on Upload file.
  5. Then hit on New Import Job >> type the job name >> Next.
  6. Check on Upload Your Date >> Next.
  7. Now, you will see a window; just click on Show Network Upload SAS URL. Copy the URL and paste it in the notepad >> Download Azure AzCopy. Click Run and the tool gets installed.Note: While you are importing PST files into Office 365, just give the permission of the folder or file that you want to import and copy the Network Path. 
  8. Open the Microsoft Azure AzCopy tool and type hereAzCopy.exe /Source: Network Path or File location /Dest:”SAS URL” /V: location path where you want to save the log file /AzCopy.log /YSample Code:AzCopy.exe /Source:\DESKTOP-MPKVU38UsersleDesktopImport /Dest:"" /V:c:UsersleDesktopAzCopy.log /Y 
  9. Press the Enter key.
  10. After uploading the PST file, create a CSV file to map the PST file into the mailbox account.
  11. Now, open the import data window and check on both options and >> Next.
  12. Click on Select Mapping file >> Upload CSV file >> Validate >> Save.
  13. Your PST file successfully uploaded into Office 365 >> Close.

Method 2: Import Outlook OST into Office 365 Using MailsDaddy Software

As we can see, the above method is very complex and time-consuming. So if you are not aware of Azure AZCopy tool or PowerShell Commands, then I will suggest that you use the MailsDaddy OST to Office 365 Migration tool. This is a GUI-based application which allows the uploading of OST file data directly into an Exchange Online (Office 365) mailbox in a few clicks only. The best thing about this tool is that you can import OST into Office 365 Primary as well as Archive mailbox as per your need. The OST to Office 365 tool is a very easy-to-use application which does not require any PowerShell commands. Quickly migrate all data of your OST files like emails, attachments, tasks, appointments, meetings, and contacts to an Office 365 cloud environment with the following steps:

  • Download and install the software on your PC.
  • Launch the tool and browse your OST file by clicking on the Add File button.
  • The software will preview all data. Click on the Export button.
  • Enter Office 365 login credentials and click on the Sign In button. That’s it.


In this post, I have described two possible ways of importing OST into an Office 365 mailbox. The first method is quite time-consuming, and the second method is very quick for uploading OST files to Exchange Online. So you can choose a method according to your requirements. If you have any doubts or queries related to this post, then feel free to make a comment. I will be happy to reply.

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