Best OST to Office 365 Migration Techniques

The article is all about the migration of OST file to Office 365 user account. Based on my own research I have shared the collected information with that one can easily perform OST to Office 365 platform. Also I have recommended a third party application which can be used to perform the OST to Office 365 migration.

Exchange Server is the most prominent mail server developed by Microsoft. It is used with Microsoft Outlook and saves the data in OST format. This OST format enable users to access the data in offline mode and synchronize with Exchange Server when it is connected. Now because of the latest technology Office 365, most of the organizations are planning to migrate their OST file to Office 365 cloud. The reason is simple as it allows user to access the emails from anywhere with having availability of internet.

At present there is only one manual method of performing the OST to Office 365 Migration that can only be used if you are connected to Exchange Server. With this method you will need to export the mailbox data in PST format which can be further imported to Office 365 account using Microsoft’s Azure tool or third party applications. There is no direct manual way of importing the OST file content directly to Office 365 account. Let us discuss that method in detail. You can also read our related article on how to convert Lotus Notes NSF to Outlook PST or Office 365.

Export your OST File Data to PST format

This method is only available if you have access to the OST file i.e. you are connected to Exchange server. Taking backup of Offline OST files to PST is not possible with this method. To covert a disconnected or offline OST file you can use a handy OST to PST conversion tool.

To export your present Outlook OST emails to PST format just follow the steps mentioned below:

  1. Open Microsoft Outlook >> click on File from Menu
  2. Select Open and Export >> Import/Export
  3. Choose Export to a File >> Outlook data file >> Choose folders that you want to convert and then click on Finish button.

This will create PST file on the desired location which will be imported to Office 365 cloud. So in this step we will first convert the OST file to PST format and then will migrate it to Office 365 cloud.

How to Import PST data to Office 365 by using Microsoft’s Azure AzCopy Tool

This method is a little complex. You will need to go with Azure Tool. It is a perfect application that allows to work with Azure Storage Data easily from anywhere and from any platform. The basic need to perform the migration with this step in Technical Skills. I would recommend you to not use this method if don’t have much knowledge above Azure Tool and Commands. Only the one has some technical skills can follow and perform the migration with these steps. You may also get detailed information here.

Step-by-step instructions to import all your data to Office 365 account

Step 1: Share the folder containing PST file on Network: In the first step you will need to share the PST file over the network. Right Click on the folder having that PST file >> Properties >> Now Click on Sharing tab and then share the folder with everyone. Copy and paste this Network path somewhere as this will be required further at the time of uploading.

Step 2: Download and Install the Azure application in your machine: The next step is installing the Azure Tool in your machine. You can download this tool directly from the official website of Microsoft or you may use this link to perform the same:

Step 3: Copy Unique key and Unique URL and paste it somewhere: The next step is to copy the Unique URL and the Unique Key. To get this URL Open Office 365 Admin Center >> Click on Import option. Now click on Upload Files Over Network. In the next step click on Show Key & Show URL.

Step 4: Launch the Azure tool to upload PST file and Run the following commands: Now run the command given below in Azure Tool. Replace “your unique URL” and “your unique key” with the keys copied in above step.

AzCopy.exe /source:\\SERVER\SHARE /dest:{your unique URL}/SERVER/SHARE /destkey:{your unique key} /S /V:C:\Logfile\ostfile.log

Step 5: Now create a CSV file for mapping with the following columns.

  • Workload: In this Column enter Exchange.
  • FilePath: Enter the Shared path of your PST file that you have got in the first step.
  • Name: Enter the Name of your Outlook PST file.
  • Mailbox: Enter the Name of the mailbox in which you want to import the data
  • IsArchive: Enter True in it if you want to move data in primary mailbox else enter false.
  • TargetRootFolder: Enter the folder name where you need to import PST file.

Step 6: Now the next step is to MAP that created CSV file.

After performing the above steps, click on next button and enter the JOB name. Now click on plus icon and then upload the CSV file to migrate data to Office 365 cloud.

The steps explained above are quite complex and may be difficult for the normal users to perform. Also, you can’t upload the offline OST file with the above suggested method. In that case you will have to use a third party OST to Office 365 Migration Tool and one such application that I have used is MailsDaddy OST to Office 365 Migration Tool.

Why Use this Third Party OST to Office 365 Migration Application?

Now you may have a question, why should I use this tool? And here is the solution, this tool provides the perfect way of performing OST to Office 365 Migration. You can directly import OST to Office 365 user account without converting it in PST format and hence can save a lot of time in migration.

This is the best standalone application that can perform the migration without Exchange Server or Outlook installation. Just follow the steps mentioned below to perform the same:

Step 1: Download and Install the MailsDaddy OST to Office 365 Migration Tool is your machine. Click on the Add File button and Browse the OST file that you want to Migrate in Office 365 User account.

Step 2: The software will preview all data. Now click on Export button, choose the Office 365 option and then click on Export button.

Step 3: Enter your Office 365 Login Email ID and Password and the tool will perform the entire migration automatically. You can track the progress of migration with Progress bar.

This way you can easily perform the migration of your OST to Office 365 environment. You can choose the method as per your convenience. If you are OK with the Azure command and some hectic task then you may go with the first method else try easy to use Third party Migration Tool. Obviously you will have to spend some amount i.e. $99 to use this application.


In this article I have explained two different methods of performing the OST to Office 365 Migration. One is by exporting the OST to PST format and then importing PST to Office 365 cloud with Azure tool and another is by using a third party migration tool to perform OST to Office 365 environment directly. Hope the above information is useful for you. Please share your feedback in comment.

Read our detailed review of the MailsDaddy PST to Office 365 tool to learn more about the features and benefits of this software.

James Anthony

By James Anthony

A senior FinancesOnline writer on SaaS and B2B topics, James Anthony passion is keeping abreast of the industry’s cutting-edge practices (other than writing personal blog posts on why Firefly needs to be renewed). He has written extensively on these two subjects, being a firm believer in SaaS to PaaS migration and how this inevitable transition would impact economies of scale. With reviews and analyses spanning a breadth of topics from software to learning models, James is one of FinancesOnline’s most creative resources on and off the office.

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