How to Open Outlook Offline OST File in Office 365?

Having your Exchange mailbox data on the cloud platform like Office 365 provides many benefits. Emails in Office 365 are widely accessible delivered you have the network connectivity. So, many Exchange users like to preserve a copy of their Exchange mailboxes into Office 365. To facilitate this simply, one can transfer their Outlook offline OST file in Office 365 accounts. And this can be achieved in different ways.

Reasons to Open Outlook OST File in Office 365

  • Organizational switch due to Office 365 benefits
  • Exchange damage or crash and require a trustworthy platform
  • Avoid big Exchange maintenance stoppage
  • Fast access to data in a secure environment after unintentional deletion

How to Open Outlook Offline OST File in Office 365?

There are no direct methods available to move OST emails in Office 365. Though, you can migrate OST data files to PST file format, and then move them to Office 365. Also, there are many third-party tools available to help you export OST to Office 365 account.

  1. Export OST data into PST, and then import them in Office 365 cloud manually.
  2. Convert OST files in Office 365 accounts directly using an automated tool.

Manual Method to Save Outlook Offline OST File in Office 365

In this indirect or manual method, you need to first convert OST files in PST format and then transfer them into O365 cloud to achieve the task of how to open Outlook offline OST file in Office 365.

Step 1. Migrate OST data into PST Format

There are three different manual techniques to move OST file in PST format.

Technique#1. Make a New PST File and Copy OST Items

This method helps to transfer mailbox items to the new PST file.

  • Open the Outlook email application.
  • Make a new PST file in Microsoft Outlook.
  • Copy data from the necessary mailbox folder and paste it into the PST file.

Technique#2. Use the Archive Feature of Microsoft Outlook

  • Open the MS Outlook and choose File Cleanup tools Archive.
  • Choose a file or folder.
  • Then browse the location where you wish to save the file and press on OK.
  • An archive is created.

Note: Complete mailbox items can be archived excepting Outlook contacts.

Technique#3. Use the Export Feature of Microsoft Outlook

  • Open the MS Outlook email client and go to the Export option from the File menu.
  • Choose the Export to a file option, and then press on Next.
  • Now, choose the Personal File Folder (PST) option and click on Next.
  • Give the saving location for the exported file and then click on Finish to complete the procedure.

Note: This process works only when the user account is linked to the MS Exchange Server.

Step 2. Upload the PST file to Office 365 account

After exporting OST in PST, you can add it to Office 365 in two different techniques:

Technique#1. Network upload with Azure AzCopy

You can directly add the PST files in O365 by using AzCopy.

  • Download and install Azure AzCopy. Now, copy the SAS (Shared Access Signature) URL (the SAS URL will offer the required permission to move the PST file to Azure).
  • Make the PST mapping (CSV) file.
  • Now, make an import job in Office 365 to import PST file.
  • Filter the data items and start the PST import job.

Technique#2. Drive Shipping PST Files to O365 Cloud

Drive Shipping to Microsoft allows importing PST in Office 365. Now, you just copy the PST files to the hard disk drive and send the drive to Microsoft. Microsoft will copy the data from the disk drive to the Office 365 cloud.

OST to Office 365 Converter – An Automated Tool to Directly Open Outlook Offline OST File in Office 365

Converting OST files to Office 365 is not an easy task. Technical and non-technical users find it a problematic and tricky task. That is why third-party applications are advised for direct OST file to Outlook Web Access conversion. Therefore, OST to Office 365 tool is a very helpful tool for this.

The OST to Office 365 software provides the simplest way to successfully fix the problem of “how to open Outlook offline OST file in Office 365?” Using this software you can perform choosy conversion from OST mailbox to O365 cloud without any issue. The conversion tool is an amazing application for both professional and novice users that is supportable with all Windows OS platforms including Windows 10. It also supports batch migration of OST items to Office 365 as same as single migration in a single process. To understand its working you can download its free demo version, which permits converting first 20 items from OST to Office 365 without any cost.


In this blog, we provided different methods to resolve the task of how to open Outlook offline OST file in Office 365. So users can choose any suitable solution according to their need. But if you need to open a few OST files into O365 cloud, then you can go with the manual method or if you need to convert bulk OST data to Office 365 account, then you should go with the automated solution.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s