• Recover, preview and directly import OST to Office 365.
  • Import Public Folders, Archive and Shared Mailboxes.
  • Extract and import Emails, Contacts, Calendars, Tasks, Notes, and Journals.
  • Import complete Metadata and Attachments.
  • Perform the import operation without any file size limitations.
  • Highly secure incremental migration of OST file contents to Office 365.
  • Compatible with all Windows Operating Systems 11, 10, 8, 7, and Windows Server 2003-2022.

(4.9/5 Rated)

Why do you need to import OST to Office 365?

An OST file is a file format stored by Outlook or Exchange server and has the entire copy of your mailbox data that can be accessed offline. OST files can get corrupted, disconnected or orphaned. When Microsoft Outlook or your Exchange server crashes, you might not be able to access your OST files or recover your mailboxes. In such cases you can migrate the contents of an OST file directly to Office 365.

Following are some of the reasons for performing the migration

  • Being a cloud service, Office 365 has many advantages.
  • Your data is stored safely in the cloud and you do not have to worry about crashes, server disasters and so on.
  • Office 365 servers guarantee 99.9% uptime and you can access the data from anywhere without worrying about data loss.
  • You can make use of the cutting edge Office 365 collaboration tools.
  • You are looking for a way to import the OST file contents from old or legacy Exchange versions.

How to import an Outlook OST file to Office 365?

EdbMails OST to Office 365 migration software allows you directly convert the contents of an OST file to Office 365 in 3 easy steps.

Install the application

Download and install the application on your PC.

Select the OST file

Browse and open the OST file to recover its contents. After the recovery you can preview the contents of the OST file.

Migrate to Office 365

You can apply filters based on Data, Cc, Bcc, Subject and migrate the OST file contents to Office 365.

Benefits of using EdbMails

Benefits of using EdbMails
  • Recover and import an OST file to Office 365 without any dependency on Microsoft Outlook, Exchange server or Active Directory services.
  • EdbMails uses OAuth modern authentication Office 365 login based on ADAL (Active Directory Authentication Library) which is a secure method to access your mailboxes.
  • The tool automatically sets impersonation rights, maps mailboxes and can even create mailboxes on the target Office 365.
  • Maintain original data & folder structure on both the source and target with 100% accuracy.
  • Perform incremental migration without creating duplicates on the target Office 365.
  • Free software updates and upgrades with lifetime licenses along with 24/7 customer support.

Features of EdbMails

Import OST to Office 365 without data loss

During the import operation, EdbMails ensures an exact copy of the source OST mailboxes in the target Office 365 tenant mailbox. Without any data loss, all of the data from the OST file will be migrated, along with all of the mailbox items and the associated mails properties ensuring the consistency of your data.

Migrate selected emails, folder and its items from OST file

Edbmails OST to Office 365 migration software allows you to select the required emails and folder in the OST file and then import it to Office 365. Selectively migrate the required items like Inbox, Contacts, Calendars folders and the items in the corresponding folders by switching to filter settings where you can set include / exclude filters based on Date, Subject, To, Cc, Bcc, Attachment Name etc.

Recover and export an orphaned OST file

When an Exchange server or MS Outlook fails, the OST file may become orphaned rendering the OST file data inaccessible. EdbMails tool comes in handy in this situation to recover the orphaned OST files and directly import OST to Office 365.

Migrate email, calendars, contacts and more

EdbMails can import OST mailbox data to Office 365 by keeping the folder structure intact. This will help you to migrate the entire mailbox including emails, contacts, calendars, tasks, journals etc., with a single click.

Secure and reliable import with Multi Factor authentication

EdbMails employs a secure OAuth Office 365 modern login based on ADAL. Furthermore, all meta-data required for migration is stored locally on your PC encrypted with a military-grade AES-265 encryption. It also supports multi-factor authentication, which increases the security of your login and migration process.

Truly incremental OST to Office 365 migration

With EdbMails software you can perform incremental migration that saves both bandwidth and time. This means that when you perform the migration from the same PC, only the newly added items are imported to your target Office 365 account on subsequent migration operations thereby avoiding duplicate items.

You can automatically reconnect during intermittent internet connection

During migration, the tool automatically reconnects and continues with the import operation to the target without data loss.

Corrupt and damaged OST files recovery

You can use EdbMails tool to recover an offline Outlook data file that has been corrupted or damaged while preserving the original data and folder hierarchy.

Granular migration of the mail items

Using EdbMails granular migration feature, you can import mailboxes, folders and any items of your choice to Office 365 from the EdbMails’s tree-view. The tool ensures that all your data is completely recovered and allows you to migrate only the items you need rather than moving the entire contents.

No third party dependencies required for OST to Office 365 migration

EdbMails can be installed on any source server or client computer. Furthermore, EdbMails is not reliant on any third-party services, DLLs, or cloud platforms. The migration occurs between the source file and the destination Office 365 server. All of your credentials are safe and secure, and will only be used for migration.

Set impersonation rights automatically on the target Office 365 account

EdbMails can automatically set impersonation rights for you without the use of any PowerShell cmdlets. Impersonation rights allow the admin user to migrate other users' mailboxes without requiring their individual credentials.

Create mailboxes automatically during the migration

Using EdbMails software, you can automatically create mailboxes on the target server and assign licenses to them. This is helpful for large scale migrations where you can directly create mailboxes from the tool.

Migrate Public Folders, Archive and Shared Mailboxes from an OST file to Office 365

EdbMails supports importing Public folders, Archive and Shared Mailboxes. The tool allows you to easily connect to a Public folder, Archive or Shared mailbox from the user-interface where you can select the required contents and import it directly to Office 365.

Map mailboxes automatically between the source OST file and target Office 365

For large-scale migrations, EdbMails can automatically map the source OST file mailbox to the destination Office 365 server mailbox for a nearest match, saving time. You can also manually map the source OST mailboxes to the appropriate Office 365 or user account mailboxes.

System requirements, supported versions and scenarios

Processor icon


Quad-core CPU with 1GHz processor. Supports both 32-bit and 64-bit systems

OS icon

Operating System

Windows 7, 8, 10, 11 and all Windows Server versions

RAM icon


512 minimum requirements.
(4GB recommended)

Hard Disk icon

Hard Disk Space

20MB free space for EdbMails installation and enough space to store the recovered output file

Outlook icon

Outlook versions

Outlook 2003 to 2019 all versions supported

Comparison of import OST to Office 365 tool Trial and Full Version


Free Trial Version

Full Version

Recover OST files  
View the contents of the OST file  
Automatically map mailboxes between the source OST and target  
Automatically create mailboxes on the target Office 365 server  
Import the entire OST file contents to Office 365 (Corporate and Technical Edition)30 items per folder 
IMAP OST file to Office 365 (Corporate and Technical Edition)30 items per folder30 items per folder
Public folder, Archive, Shared Mailboxes30 items per folder 
Technical support 24/7  
Apply filters to export selected mail items  
Log report for verification of migrated items  


  1. How to preview and import OST files with the free EdbMails tool?

    Follow the steps below to recover and open and import corrupted OST files

    1. 1. Download and install EdbMails free tool from the link
    2. 2. Browse for the Offline Outlook OST file on your PC.
    3. 3. The tool will recover the OST file and display the contents in the form of a tree-view.
    4. 4. You can select individual mails and import them to Office 365.
  2. What can I use the free version of the EdbMails tool for?

    You can use the free trial version of the application to recover and preview all the contents of an OST file. With the free version, you can additionally export 30 items from each folder of an OST file to PST or directly migrate 30 items from each folder of an OST file to Office 365/live Exchange server.

  3. How to import Outlook OST to Office 365 using EdbMails?
    1. 1. Download and install EdbMails.
    2. 2. Browse for the location of your OST file and select the items you wish to export.
    3. 3. Click Migrate to Office 365 to import the OST contents to the target Office 365 account.
  4. Can I import the contents from a corrupted OST file to Office 365?

    Yes, with EdbMails software you can recover the contents of a corrupted OST file and directly import it to your target Office 365 account.

  5. Can I migrate the contents of an OST file from Outlook 2010?

    Yes, EdbMails supports migration of OST files from Outlook 2003, 2007, 2010, 2013, 2016, and 2019 to Office 365.

  6. Can I open an OST File without an Exchange server or Outlook profile?

    Yes. EdbMails' free tool is the best solution to open an OST file without depending on an Exchange server or any active Outlook profiles. This means that you can simply open an offline OST file in EdbMails to recover and view all the contents of it. You do not need to be connected to an Exchange server or require any Active Directory services.

  7. Do I need to install Microsoft Outlook on my PC for the migration process?

    No. If you are importing the contents of the OST file into Office 365 server, there is no need to install Outlook on your system. You can directly transfer the contents to your target account without Outlook dependency.

  8. Can I import multiple mailbox content without losing any metadata?

    Yes, EdbMails is the best software to directly import all the contents without losing any metadata such as Attachments, Sent Date, Time, Headers and such information.

  9. When and why do I need to import an OST file into Office 365?

    An Outlook OST file is an offline storage file from an Exchange server or Outlook. You need to migrate OST to Office 365 in the following cases.

    1. 1. You cannot access your OST file either because it is corrupted, damaged or encrypted.
    2. 2. You need to recover the contents such as mails, contacts, tasks.
    3. 3. Your Exchange server might crash leaving you with an orphaned OST file.
    4. 4. You wish to take advantage of the Office 365 features and want to move to the cloud.
    5. 5. You are looking for a way to migrate from legacy on-premise servers to Office 365.
    6. 6. You would like to migrate the contents of an IMAP OST file to Office 365.
    7. 7. You want to eliminate the storage issues, support issues, compliance issues, and eDiscovery migration issues that OST files cause for many enterprise users.
  10. How does EdbMails ensure a successful import or migration operation?

    The tool maintains an exact copy of the source mailbox in the target Office 365 account. For example, after importing an OST file to an Office 365 all of the mail data in the target account is an exact replica of the data in the source, with no changes. The application ensures that no data is lost or corrupted during the process in this manner.

  11. Can I migrate the contents of the OST based on a specific Date or Sender?

    Yes, With EdbMails you can choose to migrate the contents based on specific date, senders or even the subject. There are many filter options using which you can selectively export the contents instead of importing the entire source file to the target account.

  12. What items can I migrate with the EdbMails OST to Office 365 tool?

    EdbMails migrates mail items, calendars, contacts, Alias Distribution Groups, Tasks, Notes, Journals, Public Folders, Archive, and Shared Mailboxes, meeting invites, and so on.