OST to PST file converter
Recovery Toolbox for Outlook
How to convert OST to PST
How to convert OST to PST file
Updated: 2026-02-25A step-by-step manual for the conversion of Exchange Server OST files to Microsoft Outlook PST files. This instruction helps to convert OST to PST files with all messages, contacts, appointments, tasks, notes, journals, calendars and so on:
- Download Recovery Toolbox for Outlook here https://osttopst.recoverytoolbox.com/download/RecoveryToolboxForOutlookInstall.exe
- Install Recovery Toolbox for Outlook in Windows
- Start Recovery Toolbox for Outlook
- Select an OST file on the first page of the program
- Select the Converter mode mode
- View the content of the OST file
- Select a folder for saving converted data
- Select the Save as PST file mode
- Click Save
OST to PST Converter Free
OST-to-PST conversion is an added feature of Recovery Toolbox for Outlook. The OST to PST Converter Free can convert .ost files from any version of Microsoft Outlook or any version of Microsoft Exchange Server into the .pst file format without Exchange Server or Windows Domain Controller. Customer can convert ost to pst online on any device in Windows, Android, macOS, iOS and so on.
Features of OST-to-PST conversion software:
- Converts *.ost files of Microsoft Outlook 97/98/2000/XP/2003 (ANSI .ost files)
- Converts .ost files of MS Outlook 2007/2010/2013/2016/2019/2021/2024 (UNICODE .ost files)
- Converts password-protected files
- Converts encrypted .ost files
- Converts damaged .ost files
- The ability to split the output pst file into several volumes of a maximum size defined by the user
- The ability to save items as MSG/VCF/EML/TXT files
- Converts *.ost files after failure ScanOST recovering
- Converts *.ost files without connect with Windows Domain Controller
- OST2PST conversion without Microsoft Exchange Server
- Converting OST to PST for files of more than 4 GB
- Import of OST files of Microsoft Exchange Server
- Import of OST files of Office365
- Import of OST files of MAPI server systems
- Opens OST files of any size and version for free
- Opens damaged OST files for free
- Reads and analyses damaged OST files
- Shows the content of OST files for free
- Finds and repairs data from OST files for free
- Saves data from OST file to PST file
- View OST file
- Microsoft Outlook Recovery
- Repair Microsoft Outlook
- Fix Corrupt OST file
- Fix.PST file
- PST to EML
- Outlook Viewer
- 0x8004010F
- Outlook Repair 2019
- Outlook Repair 2016
Import of OST files in Outlook
Recovery Toolbox for Outlook helps to import OST files in Microsoft Outlook in a few easy steps:
- Start Recovery Toolbox for Outlook
- Select or find on the disc OST file on the first page of Recovery Toolbox for Outlook
- Select the mode Conversion
- Select folder for saving PST file with data
- Start Microsoft Outlook
- Delete the OST file from system settings. Menu: File | Account setting. Tab menu Data file
- Open saved PST file in Outlook through menu: File | Open&Export | Open Outlook Data File
Recovery Toolbox for Outlook is OST-to-PST converter and an Outlook OST recovery tool at once.
Requirements:
- Windows 98/Me/2000/XP/Vista/7/8/10/11 or Windows Server 2003/2008/2012/2016 and above
- Microsoft Outlook 98, Microsoft Outlook 2000, Microsoft Outlook 2002, Microsoft Outlook 2003, Microsoft Outlook 2007, Microsoft Outlook 2010, Microsoft Outlook 2013, Microsoft Outlook 2016, Microsoft Outlook 2019, Microsoft Outlook 2021, Microsoft Outlook 2024 must be installed on the user’s computer at the time of conversion (excluding Outlook for Office 365, Outlook for iOS and Outlook for MacOS).
Notes:This product does not export contact groups
The extensions of recovered files: pst and ost. The Online Service and Recovery Toolbox for Outlook repairs files Microsoft Outlook 98 / 2000 / 2002 / 2003 / 2007 / 2010 / 2013 / 2016 / 2019 / 2021 / 2024 and Outlook for Microsoft 365.
FAQ-Wiki:
Question:
Can an OST file be converted if its size exceeds 50 GB?
Answer:
Yes, it can. Converting an OST file with a size of approximately 50 GB takes several hours on a computer with a good processor clock speed and a fast disk subsystem.
The recovery time for an OST file of about 50 GB is several days on the same high-performance computer.
Question:
Does the version of Windows affect the success of converting OST to PST?
Answer:
The version of Windows has no bearing on the success of converting OST to PST.
Question:
Does the service support the recovery of nested attachments (nested emails, attachments in .msg inside emails)?
Answer:
Yes, the service copies or recovers all types of nested objects and files, including those with .msg extensions.
Question:
What should I do if the PST file does not open correctly in Outlook after recovery?
Answer:
The PST file may not open in older versions of Microsoft Outlook 97-2003. Older versions of Outlook only support PST files in ANSI format. Earlier versions of Microsoft Outlook, starting with Outlook 2007, use the Unicode version of PST files.
Question:
Can I convert multiple OST files at once (batch conversion)?
Answer:
No.
Question:
Are email categories and colors preserved during recovery?
Answer:
Yes, of course. Email categories and colors are transferred to the new converted or recovered PST file.
Question:
Are contacts and their photos recovered from the OST file?
Answer:
Yes, of course. All contact data, including photos, is transferred from the OST file to the PST file.
Question:
Is it possible to select specific folders for conversion, rather than the entire OST file?
Answer:
Yes, of course. On the second page of Recovery Toolbox for Outlook, you can select folders or individual emails, contacts, and other items to export to a PST file. The online OST to PST conversion service copies all content from the PST file without the option to select specific items.
Question:
What happens to emails that are marked as deleted but not deleted from the OST file?
Answer:
Messages marked as deleted but not permanently deleted are located in the Deleted folder. The Deleted folder and all its contents are transferred to the PST file completely as is. If the Deleted folder is emptied, the messages from it will not be transferred to the PST file.
Question:
Is it possible to recover only attachments from the OST file, without emails?
Answer:
Unfortunately, there is no function to split emails into separate files and objects. It is not possible to save only attachments without emails separately.
Question:
Will the calendar and all its reminders be recovered?
Answer:
The calendar, reminders, and all their settings are transferred to the PST file in their entirety.
Question:
Are there any restrictions on restoring password-protected emails or PST files?
Answer:
Password-protected emails or the contents of password-protected OST files are transferred to PST files in their entirety, and the passwords are removed. These files and emails do not require passwords to be entered in the future.
Question:
Are signatures and email processing rules from OST restored?
Answer:
No. Signatures and email processing rules are stored in the Windows registry, and these settings are not transferred to OST files.
Question:
Can the service be used to extract data from OST files created in Office 365?
Answer:
Yes. Data from OST files created in Office 365 is transferred to the PST file in its entirety.
Question:
Can items created in Outlook Web Access (OWA) be recovered through the service?
Answer:
No.
Question:
Will nested folders and their structure be recovered?
Answer:
All nested folders and folder structure are transferred from the OST file to the PST file in full and in the same form as they are in the OST file.
Question:
Is it possible to recover after a failed mail migration between Exchange and Outlook?
Answer:
Yes. It is common for migration to fail and for each user's file to have to be converted to a PST file. The service and the Recovery Toolbox for Outlook program successfully convert such files to PST files.
Question:
What about drafts and unsent emails?
Answer:
The “Unsent” and “Drafts” folders are transferred to the PST file along with all emails.
Question:
Are read and unread marks preserved after recovery?
Answer:
Yes, all “Read” and “Unread” service marks are retained for each email, as in the original OST file.
Question:
Are there any differences in restoring OST files from different versions of Exchange?
Answer:
No. All OST files from different versions of Exchange Server are correctly read, converted, and restored to a PST file.
Question:
Does the service work with files damaged by viruses or malware?
Answer:
Yes. Malware or viruses usually encrypt the beginning and end of a file if the files are large. The service and Recovery Toolbox for Outlook read the entire file and extract unencrypted emails, contacts, appointments, and other data to the maximum extent possible.
When a PST file is encrypted by a virus or malware, advanced settings and user data settings stored at the very end of the OST file are often affected.
Question:
Can I use the service to retrieve data from an OST file if the account no longer exists?
Answer:
Yes. Very often, an account is blocked, deleted, or control over it is lost, but the service and Recovery Toolbox for Outlook convert OST to PST for subsequent use in Microsoft Outlook.
Question:
What email metadata (e.g., hidden fields) is preserved during conversion?
Answer:
All email metadata, especially service headers, is transferred to emails during conversion.
Question:
Is the service compatible with OST files created on corporate networks with restricted access?
Answer:
Yes, the service converts OST files created in corporate networks with restricted access.
Question:
Is it possible to recover a mail archive if some of the data was automatically archived by Outlook?
Answer:
Yes, if the data was archived as a PST file.
Question:
Does recovery work with encrypted OST files?
Answer:
Yes, encrypted OST files are recovered just as quickly as unencrypted ones.
Question:
Does the service support the recovery of attachments that were modified after the email was downloaded (for example, edits in .docx)?
Answer:
Yes, the service converts all attached files in the form in which they are stored in the OST file.
Question:
Is it possible to obtain logs or a report on the progress of OST file recovery?
Answer:
OST file recovery logs are available on the last page of the Recovery Toolbox for Outlook program and in the err.log file. The online service does not provide conversion logs.
Question:
Is it possible to integrate the service with PowerShell or API for mass automation?
Answer:
No.
Question:
Can the service recover Notes, Tasks, and Journals from an OST file?
Answer:
Yes. All Notes, Tasks, and Journals are transferred completely from the OST file to the PST file.
Question:
How can I recover an OST file if it was synchronized with Exchange Server, but the server is no longer available?
Answer:
Simply open the OST file on the first page of Recovery Toolbox for Outlook or the first page of the online conversion service, and then convert the data from the OST file to a PST file.
Question:
Are attachments within calendar events saved?
Answer:
Yes, all attachments within the calendar are saved and transferred.
Question:
Is it possible to get a list of contacts separately, in .csv format?
Answer:
Contacts can be saved separately as .vcf and .msg files. Simply select the desired contacts or contact folder on the second page of Recovery Toolbox for Outlook and select a folder on your disk to save the contacts. Each contact will be saved as a separate .vcf or .msg file.
Question:
Can the service work without Outlook installed on the computer?
Answer:
Yes, but then the saved data can only be exported to .msg and .eml files. Exporting data to a PST file is only possible if you have the desktop version of Microsoft Outlook installed.
Question:
Is there a guarantee that the data will not be disclosed to third parties after recovery?
Answer:
Recovery Toolbox for Outlook runs locally and does not transfer data to the Internet. The online OST to PST file conversion service does not transfer data to third parties and is ready to sign an NDA with customers who want these guarantees of non-disclosure of data. Thirty days after uploading files to the service, all data is automatically deleted, including all logs and intermediate files.
Question:
Is it possible to selectively recover by date or sender?
Answer:
Yes, this is possible in Recovery Toolbox for Outlook. Select the desired data on the second page of Recovery Toolbox for Outlook, and only that data will be converted and saved.
Question:
How does the service work with emails containing digital signatures?
Answer:
Letters and their contents are transferred to a PST file, but digital signatures are not transferred correctly.
Question:
Is correspondence information (threading, letter chains) restored?
Answer:
Letter chains and links to the parent object are transferred.
Customer's reviews and ratings:
good tool
Impresionante, no imaginé tal eficiencia, muchas gracias.
These guys are great. I was able to recover the 5 most recent emails from each and every sub folder. This is the free version. It's a life (email) saver. Thank you.
80 años. Retirado. RECOVERY,TOOLBOX, facilísimo de usar. Fabuloso.
This is gold.. loved the service
I accidentally deleted files in my email inbox, and I was able to recover many of the deleted files using your tool.
:=)
I lost the files after a computer crash.
Had to re-install windows.
I want to recover all pst, and ost. Files.
canot tell 100000000 thanks
Repairing a damaged PST file. I was able to recover most of my emails.
nice
Excelente programa, mis felicitaciones.
super recovery, very fast and did a perfect job, can recommend to any one looking for recovery software.
100% ist Gut!
Hello Recovery Toolbox team,
thank you very much for your support. One of my PCs froze, forcing me to do a hard reset. At the time, Outlook was open. After the restart, Outlook could no longer find the PST. Renaming the PST wasn't possible, even in safe mode. Apparently, a program was accessing the PST even though Outlook was closed on all computers. A Google search led me to your tool. After the repair (2-3 hours), I was able to save the PST under a new name and use it again.
Thanks again.
Best regards, Dietmar Kroschel
I needed to access OST files on an old hard disk. As I don't use Outlook as email client, I needed to find a tool. I was not recovering from corrupted data.
Thanks for making the tool👍
Feels good! i like it! thnx for devs
its workilng very well in 2025 thank you
Great program, really helped me out!
Excel.lent! I couldn't with other applications and this one worked the first time!
Good program
sir best softwear for everyone . Thanks
Tank you very very much the software is help full
Had my agenda only in the ost, so not synched to the webmail.
After making a new profile my agenda items were gone. Used the Recovery tool for Outlook to restore the items to a PST from a backup of the old OST files. And then copied them back to my agenda.
This worked well although only the agenda item are restored, not the attachments and extra information field.
VERY GOOD
Really works. It identifies the bad sectors and skips them while getting rest of the data out.
Love it.. except.. you should consider including a PAUSE/RESUME button. Just sayin'. Thanks.
I wanted to send a large pdf file (20Mb).
While sending I disrupted this process (turned off pc?). As a result I had an unclosed mail in my pst-file. As a result my pst-file was corrupted and my outlook could no longer be started/opened.
This tool fixed PST-file.
Recovery Toolbox for Outlook was able to convert an .OST to .PST, but the ability to open the .PST is missing. The help text says it is under the File menu, but all that is there is "Exit".
Хорошая вещь! Отлично справляется, за секунду исправил испорченный файл.
I don't know if the files were damaged, but they could well have been. These two files were backups of PST files that I had made before transitioning from the POP mail protocol to IMAP.
IMAP attached itself to my original emails and, apparently, those stored as backups. Then all the open folders in Outlook began to disappear until there were none remaining. I had no clue what had happened. I couldn't imagine they were hijacked and held at the mercy of my ISP. Then IMAP somehow transformed my PST backup files into OST files, which Outlook 2024 cannot read.
The Toolbox was able to quickly and efficiently recreate the files as PST.
That allowed me to restore and open every one of the 24,000 files.
Later, I learned that IMAP doesn't just sync emails created after its implementation but every file that it automatically and without permission opens in Outlook. I was unaware that this caused me to exceed my storage limit, leading to the disappearance of my 24,000 emails.
It is a hazardous, intrusive, and damaging protocol. It is also a potentially lucrative source of business for your company.
Best
nice
I exported from Oulook 365 a folder with a lot of e-mails, ans had a .pst 2,28 Go file. Then, I did a factory reset of my PC. I could of course import the pst file in Outlook, but I did not wanted to do that, in order to avoid duplicates in Outlook. So, I used Toolbox recovery to convert the pst file in msg, ans I copied and paste the msg files in Outlook, and it worked perfectly.
I am using Microsoft Outlook and for some unknown reason I was unable to export my OST file to PST file.
Windows stopped working properly and I had to restore it. It went well, but I lost all the applications that were not part of Windows, such as Microsoft Office.
I reinstalled Microsoft Office but Outlook can't open the OST file. So I had to use Recovery Tollbox to convert it to a PST file.
Everything went well and I recovered my old emails and contacts.
Okay, here is the why I am so frustrated at the moment with the recovery of emails from Outlook.
Apparently, there was an upgrade to Outlook that my system allowed and the program would not load. I followed instructions on how to get it to load from MS support forum and it finally loaded however all my contacts were lost. Again, following MS support I deleted the email account and reinstalled it and that is when everything went south in a big way.
Now I had some of my contacts back (from the cloud) but none of my stored files inside Outlook. I purchased the Recovery Toolbox to retrieve those files. While running the program I could see the files being recovered in the folders and subfolders that they were originally stored in. But, when the recovery was complete the files were not in the folder and subfolder in my Outlook but in individual unsorted and ungrouped emails. That said, the folders and subfolders did come over as they were supposed to on my Iphone! Well, now Outlook determined that I am over quota on emails and will not let new emails arrive.
I deleted as many non-essential emails, files and folders that I could in Outlook so that I can receive a few emails before I have to delete some more. I AM AFRAID TO DELETE OR MOVE ANY OF THE FOLDERS AND SUBFOLDERS ON MY IPHONE FOR FEAR THAT I WILL LOSE THEM.
So, I want to get away from Outlook so downloaded em Client but when I try to allow Outlook to download my main email to the new program I get the error “there was an error obtaining credentials via oAuth”.
And that is where I am, stuck with no way to consistently receive emails on my main email address and no way to move my emails to a new program. Also, I am really afraid that I will lose all the folders and subfolders on my Iphone if I don’t get them saved to a hard drive or somewhere else.
Excelente Aplicación
Hello.
I don't know exactly what I expected, but probably more than I got.
It may well be that my emails were recreated but all emails are empty. I can see sender and recipient but that's all.
I had probably hoped that some emails could be recreated so that I could read the whole email. But no waste of money.
Kind regards
Kuno Nielsen
all perfect ! good job thanks
Çok Güzel bir program.
Excellant software
Dear Support,
Glad to tell my story here what went wrong.
I had this new e-mail account in Japan which I wanted to add to my Outlook.
I have a windows 11 laptop with the new outlook.
The e-mail account is a pop3 account, but I could not add it to my outlook.
Adding it to my Android phone worked.
Adding it to another PC with Windows 10 and the old outlook worked as well.
So I thought the new outlook was to blame here and switched it back to the old version ( there was switch button in the outlook to do so) And yes, I could add the new account ( late at night)
Next morning, starting outlook and collecting mails from several accounts worked for all but one.
For one account it suddenly wanted to know the password, but did not accept it.
Inspection of the accounts then learned that Outlook had all my E-Mail accounts converted to IMAP accounts.
(except for the Japanese account added the night before.)
This seemed to work for all account but one.
So I was stuck with this one account in IMAP which needed to be POP3 Account.
First I had to recover this E-Mail account via the Web interface putting password and security codes several times.
So I googled the Internet on how to convert IMAP to POP3 and I learned you just have to delete the IMAP account and create a new POP3.
Here is where the real trouble started....
I figured out that I need a backup, but saved then the .OST files instead of the .pst files, not knowing there is no easy way to get from .ost to .pst.
So I could set up the new account and load my E-Mails from the last weeks, but the folders I missed.
That’s where I came across your tool and could convert the .ost file.
So partially I can put the blame on Microsoft for not accepting the POP3 account in the new outlook and setting existing accounts to IMAP, Partially on me, for not saving the correct .pst file but the .ost instead.
Maybe you can do something with this information.
Kind regards,
Paul van Eden.
Great tool
Simple but useful application
Excellent program
After my computer crashed due to some updates, I had to do a factory reset but keep my data. Unfortunately, all my archived emails after a certain date last year were lost. I've tried all sorts of solutions with limited success, including another recovery tool. By chance I found Recovery Toolbox, and it turned out that with the help of this product all my emails were recovered and neatly placed in the xxx.pst file, as they were before the failure.
good software
very well done application. Thank you
Excellent on-line service. The conversion from OST to PST was quick, accurate and at minimal cost.
Thank you.
Was converting large ost file (14gb) to pst. Recovered all my emails , great software ..