A Beginner’s Guide to Migrate OST to Office 365

migrate ost to office 365

Are you looking for a solution to migrate OST to Office 365? Then this technical guide will be beneficial to all users. In this blog, first, I will discuss some common reasons to choose Office 365 over Microsoft Outlook. Moving ahead, I will mention various procedures to upload OST to Office 365. In addition, you will simply use a third-party utility, OST to Office 365 Converter efficiently. 

Nowadays, OST files store copies of users’ contacts,  email messages, and other data.  When users are using MS Outlook in offline mode with the Exchange Server. In today’s world, when users do the migration process, it is a very tedious task. So they shift to Office 365. Furthermore, I will discuss some reasons that will clear all your doubts. 

Why Users are Preferring Office 365 Over MS Outlook? 

  • Numerous organizations opt for Office 365 due to its advanced features. 
  • Every user requires an efficient platform and subsequent Exchange breakdown.
  • Office 365 mailbox items can save more emails than OST files. 
  • Accidental Deletion of crucial data.
  • It also provides much better security features.
  • It is a more suitable email client rather than MS Outlook.
  • You can access data in a safe environment after deleted accidentally. 

Here, I have highlighted some of the common reasons regarding Office 365. I hope that you have got an idea why there is a need to import OST file into Office 365.  

How to Migrate OST to Office 365?

There is no direct manual method to upload OST to Office 365. You need to go through with different phases to import Outlook OST to Office 365. 

  1. Move OST files to PST file format.
  2. Add Resultant OST Files to Azure Storage or Drive Ship to MS Office 365
  3. Import Converted Outlook OST Files into Office 365

Moreover, I will highlight a third-party utility that will help you to transfer OST files to Office 365 easily.  

Step 1: Move OST Files to PST File Format 

  • First, open the Outlook application > File tab.
  • After that, Click the Open & Export tab > Import and Export option.
  • Then, select Export to a File > Next button.
  • Now, pick the Outlook Data File (.pst) > Next button.
  • Afterwards, select the desired folder to import and continue the process.
  • Furthermore, set a desired location for the resultant PST file on your local system. Now, select to replace duplicates with the items exported option.
  • In the end, click on the Convert button to export the OST to a PST file.

Step 2:  Add Resultant OST Files to Azure Storage or Drive Ship to MS Office 365

After the conversion process between OST and PST files, you need to add your OST files to Azure Blob storage. It is a command-line-based utility. In simple words, we need a command to run this tool. 

You can also utilize the Drive Shipping procedure, where you are willing to copy all the resultant OST files. You need to put in a BitLocker-encrypted hard drive (2.5 inches). After that, ship the local drive to the data centers of Microsoft. Microsoft will add the PST files to Azure Blob storage on the user’s behalf. In addition, it will charge $2/GB or $2000/1000 GB of PST files.

Step 3 Import Converted Outlook OST Files into Office 365

Moving ahead, you require to make user accounts on Microsoft Office 365 > allot licenses > construct a CSV mapping file. After that, you need to add it > allot an Import Export role > launch the import job. Then, you require to migrate the resultant OST files into O365 mailbox items. It will consume a lot of time to import all mailbox items on O365. Further, Office 365 also has some restrictions while importing PST files. When your PST file is larger than 20 GB, it may lead to stopping the importing process. 

Therefore, I have successfully finished the manual method. But, such a procedure is too much lengthy. Even technical users face so many challenges while performing it further. If you do not want to face any such issue, you can go with a third-party utility. I will mention it in an upcoming section. 

Automated Solution to Migrate OST to Office 365 

 OST to Office 365 Converter tool that aids in adding OST file into Office 365 efficiently. Users can migrate their OST files to Office 365 along with its attachments. It also import OST to Gmail, Yahoo mail and other email clients. It also provides a hierarchical folder. In fact, there are zero chances of losing crucial data during the migration process. 


Here, in this technical guide, I have gone through various topics, and hope you have got enough information. After that, I have discussed different procedures to migrate OST to Office 365. You can opt for any of them, as it is up to you. 

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