Convert Outlook OST into PST format or Office 365 Mailbox


Outlook is one of the most used Desktop email client that is used to manage multiple E-Mail accounts from the single interface. It provides lot of features to the user for email management. Internally it stores the data of those emails into the OST file format when user connected with Exchange Server with Cached mode enabled. OST file is also created when a user configure IMAP accounts in Outlook 2013 or above versions. But an OST file can be accessed locally from the machine and becomes inaccessible when we try to use it with other profiles or accounts. Due to this disadvantage users are now migrating their data to the latest project of Microsoft i.e. Office 365. It is cloud based services which allow users to access their data anywhere from the world with having availability of internet.

In this article I am going to discuss some ways of doing the OST to PST or Office 365 Migration. Just follow the step by step procedure mentioned below to perform the entire migration.

Method 1: Export OST into PST and Office 365 by Manually

Most of the users are searching the direct manual method for importing OST file data into Office 365 Mailbox but presently there is no such direct process available to move from Outlook OST to Office 365 Exchange Online. So first you have to convert OST into PST format after that you can migrate from PST to Office 365 Cloud Platform.

So let’s discuss the manual method for converting OST into PST and Office 365 Mailbox account. Just follow all the given step by step instructions to upload or convert OST file into PST and  Office 365.

Step 1: Convert Outlook OST files data into PST format

Know the process for converting OST file data like emails, contacts, calendars, appointments, and attachments etc into Outlook PST.

Open your Microsoft Outlook and click the File. Then go to Import export option.

Now a new window will open on the screen then select the Export to a file option and hit next.

After that, choose Personal Folder File (.pst) option>> Next.

Once you hit next you will see an include sub folders option, check that and click next.

When you have done, you need to provide the location to store the PST file and click finish.

Put the password if you need or hit OK.

Note: This manual process will not work when your Exchange Server is Offline and you are not connecting to the Server. In this condition, you need to use the third-party tool. So here I am suggesting one of the best tools which are MailsDaddy OST to PST converter. With this software, you can also convert your corrupted or offline OST file data into PST or other formats like MSG, MBOX, and EML etc.

Step 2: Upload PST into Office 365 Exchange Online

Once you convert the Outlook OST into PST format, it will easy to upload it in the Office 365 Exchange Online environment. Follow all the instruction to move from PST to O365 Cloud Platform.

Step 1: Login with Office 365 Admin account and go to Exchange admin center window >> permission and add Mailbox Import Export option.

Step 2: After that go to Data Migration and Upload the PST file by clicking Upload PST file.

upload PST.png

Step 3: Then New Import Job >> type the job name>> Next>> Next.

Step 4: Once you done, a new window will open on the screen, here click Show Network Upload SAS URL and hit on copy to clipboard. After that click Download Azure AzCopy and install or lunch it.

Step 5: Now type the given command on the AzCopy tool.

AzCopy.exe /Source:\\network path /Dest:”SAS URL” /V: give location  to save log file \AzCopy.log /Y

Azure tool.png

Step 6: Go back to the import data window and check the both given option>> Next.

Step 7: After that create the CSV file.

Workload FilePath Name Mailbox IsArchive TargetRootFolder
Exchange backup.pst FALSE

Step 8: Upload CSV by clicking Select Mapping File >> Validate it and click Save.

Note: You can also use any third-party software to make easy this manual process. Here I am suggesting you the best application which is MailsDaddy PST to Office 365 Migration Tool for importing PST file data into O365 Exchange Online environment within a few clicks.

Method 2: Migrate OST file data into Office 365 directly using the tool

Sometimes the users are not comfortable with the manual process, because it is very time-consuming process. In that process you also need the good technical skills and knowledge about PowerShell commands.

That’s why I am going to discuss the best method for importing OST file data into Office 365 Exchange Online environments which is the third-party solution. But it’s very important to choose a best tool because at that time many applications are available in the market. So I am suggesting you the MailsDaddy OST to Office 365 Migration Tool, to get the better result. It is very easy for the technical and non-technical users.

The Software has many advance features for our users like:

Preview the OST file data: Once you upload the OST file into the application. It will show the preview of all OST file data with the attachments.

Migration of Selected Items Only: After showing the preview you can easily select the items and you can easily search the mail by name, subject and with the data range filter.

Import multiple OST to multiple Office 365 mailboxes: The software provides the two advance features which is Bulk Export and Impersonation options. With these options you can easily export multiple OST into Office 365 Exchange Online environment by creating a CSV file.

Note: While you are using the Impersonation Option you need to provide the Application Impersonation permission and full access to the Admin Mailbox account.

Create Log File: When you are Importing OST to Office 365 by using this tool. It will create the Log File and you can save this file where you want to save.

Follow all the instruction to know how the MailsDaddy OST to Office 365 Migration Tool works:

Step 1: Firstly, you need to download the install the tool on your PC.

Step 2: Now open the installed OST to Office 365 Migration Tool.

Step 3: Click the Add File option to upload OST file into the application.

Step 4: Once you upload the OST it will show the preview of all OST file data.


Step 5: Now migrate the OST to O365 by clicking Export Button.

Step 6: After that select the required option and click Export option. At the last sign in with the Office 365 account. That’s it.




In this post, I have explained, “how can we convert Outlook OST into PST and Office 365 Cloud Platform”. I discussed two possible methods of doing the same; you can use any one of them, but as per my personal experience I would recommend you the MailsDaddy OST to Office 365 Migration Tool to upload the OST into Office 365 easily. If you have still any doubt just leave a message on the comment box. I will be happy to help you.



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