Oftentimes, Microsoft Outlook users who are leaving their current employer want to take their mail, calendar, or contacts with them and do one of two things: delete the Microsoft Exchange account from their profile without realizing the Contacts are stored in the Exchange account or they take the OST file with them, not realizing it can only be opened using the account that created it.
If you have the OST file but no longer have access to the computer that created the OST or you don't have a restore point, you'll need to use a tool to recover the contents of the OST. A list of these tools is below.
Beginning with Outlook 2013, Outlook was designed to permanently delete the OST data file when the account is removed from Outlook. If you deleted the account from Outlook and did not export the contents to a pst file or copied the OST file, your chances of recovering data is not good. You will need to use software to undelete files from your hard drive, but successful recovery depends on how much time has passed between deleting the account and running the undelete software as Windows will overwrite the deleted files. To see if the OST exists, type or paste %localappdata%\microsoft\outlook into the address bar of File Explorer. Many of the companies that have OST to PST recovery software also have file recovery software.
If your company uses a group policy that blocks PST creation, your choices are limited to exporting calendar and contacts to CSV (or Excel, if you have Excel at home). If you don't have many calendar or contacts, you can forward them to a personal address. If using Outlook 2007 or newer, you can send your entire calendar as an iCal.
Check company policies before taking home the contents of your mailbox.
Restore Exchange Account
If you deleted the Exchange account, you may be able to recover the account if your operating system supports system restore and you only recently deleted the account. If too much time has passed you are less likely to have a restore point available.
This method will also work with IMAP accounts in Outlook 2013 and up IF you have a copy of the IMAP data file.
Outlook 2013 and up automatically delete the account's OST file when the account is removed from Outlook. The only way you'll be able to use this method is if the OST file exists (because Outlook failed to delete it. It's rare, but it does happen.) To check, look for the OST at %localappdata%\microsoft\outlook before doing a restore.
- Open the System Restore application. In Settings or the Search field on the taskbar or Start menu, type restore then select Create a restore point in the search results. Click the System Restore button to open the System Restore wizard. You can also open it by typing or pasting rstrui.exe in search field or in the Run command.
- Pick a date just before the profile was deleted then follow the steps in the wizard.
When Windows restarts the account will be back and you can move or export the contents of the OST to a PST. Then either delete the account or run restore again to return to the point made before the restore, after backing up a copy of the newly created pst file.
Method 1: Archive
You may be able to use Archive to move or copy many items to a PST. Users Exchange online archive mailboxes will not be able to archive to a pst.
Autoarchive works best when you want to move almost everything in your mailbox, however, you cannot archive Contacts. You'll need to move or copy contacts to the pst file or use Export.
Set the AutoArchive default in File, Options, Advanced, AutoArchive and apply the settings to all folders. (The AutoArchive button the Folder ribbon allows you to set a specific archive setting for the current folder.)
Then go to File, Tools, Cleanup, AutoArchive to run it.
AutoArchiving uses the last modified date so you'll need to use a low number of days when archiving recent items. In Outlook 2007 and newer, you can force AutoArchive to use the Received Date. See Using Microsoft Outlook's Autoarchive feature
If you use this method and also need the Contacts, you'll need to move them to the new data file.
Method 2: Export to a PST
Although Export is not usually recommended, it works well for moving content from an OST to a PST file. You can export all content from the OST to a PST or just the calendar and contacts. If your company blocks the creation of PST files, export Contacts, Calendar, and Tasks to CSV or Excel format.
You'll use this method if you are moving to a new server and need to migrate your own email (or if the server died and there are not backups). Make sure you start Outlook offline so that you don't connect to the new server; connecting to the new server has the potential to delete the mail in the offline file. Export everything to a pst then remove your account and use auto account setup to add it back to your profile.
Method 3: Move the items to a new PST
Create a new PST in your profile and drag the folders you want to take with you to the PST. This method will preserve custom views and forms published to folder.
Dragging default folders, such as Inbox, Calendar, and Contacts, brings up a message that you can't move default folders. The contents will be copied instead, with the folder named Inbox (1), Calendar (1), etc.
Method 4: Forward by E-mail
If you don't have too many items you want to keep, you can email them to your personal email address. Select the item(s), right click and choose Forward or click Ctrl+F. If you have a lot of messages you want to keep, you could drag them to a folder in Documents, then zip the folder and email the zip file.
If you forward the messages to an account that is opened in Outlook, you can drag attached messages from the incoming message and drop it in the Inbox or another folder.
If you are using Outlook 2007 or newer, you can email the entire calendar as a single iCal, provided you use Outlook or another calendaring application that supports multi-event icals at home. Outlook 2003 and older versions of Outlook do not support multi-event icals.
To create the iCalendar file, you can right click on the Calendar folder and choose Share, Email Calendar. If you want to create the iCalendar file and do something with it later, select the calendar folder, then go to File, Save Calendar.
When you use Email calendar, a dialog will let you choose the date range and other options. If you are saving the calendar to your hard drive, click More Options in the Save as dialog to open this dialog.
The defaults are Today and Availability only; you'll most likely want to use whole calendar and full details. Note that some calendars don't support attachments; if you are including attachment you should save a second copy that does not include attachments.
OST to PST export utilities
If you have an orphaned OST and can't recover the account using System Restore, you'll need to use a utility to export the contents to a pst file.
The free OST2PST utility will only work with OST files created by Outlook 2002 and older. If you aren't sure what version of Outlook you used, try it; an error means the OST is not the correct type.
Tools in the Spotlight
Stellar OST recovery software is the most efficient tool to convert Outlook OST file to PST file. The software successfully recovers all the components of .ost file such as emails, contacts calendar entries, attachments etc. The tool is able to convert OST file to working PST file in any instance of corruption. Free demo version is also available that previews all recoverable items of inaccessible .ost file. |
Tools
OST PST viewer is a free and powerful tool that will help you to open and work with OST, PST and other Outlook file formats without Microsoft Outlook installed. It can open orphaned or any size files created by any version of Outlook. PST file viewer is the right tool for users who have lots of PST files and don't want to connect each of them to Outlook. With the enterprise edition, you can change read/unread or follow up status of emails. New version includes fixes and additional modifications. | |
OST2 Free Edition can convert up to 5 items in each folder of orphaned OST file. Use Enterprise Edition to convert and transfer all OST files to Microsoft Outlook. Import and export OST and PST files, from and to Microsoft Outlook, Exchange, Office 365, Outlook.com, Google and G Suite. Updated OST2 comes with improved performance of the software. Updated OST2 Software includes better handling of big Outlook data files and better handling of the application on different computer environments. | |
DataNumen Exchange Recovery repairs and recovers corrupted Microsoft Exchange offline storage (.ost) files. Exchange Recovery can scan orphaned OST files and recover mail messages and other items, including folders, posts, appointments, meeting requests, contacts, distribution lists, tasks, journals and notes. The recovered items are saved in PST format readable by Outlook, Other important features: recover attachments and deleted items, recover oversized 2GB OST files, support to convert OST files into PST files. | |
DataNumen OST to PST Converter converts Outlook OST files to PST files: Convert of ALL Outlook items with ALL properties. Supports converting corrupt or damaged OST files. | |
Kernel for OST to PST software is the one-stop solution for all OST file corruption issues. It effectively repairs corrupt OST file and converts it into Outlook accessible PST file format. Individual email items can be saved in different formats including PST, MBOX, TXT, RTF, HTML, EML, MHTML, MSG and PDF. It also provides option to export OST files to Office 365 and different email servers and web mails. It supports all versions of MS Outlook (2016), MS Exchange Server (2016) and Windows OS (Windows 10). Free trial version of the tool is also available. | |
Kernel OST Viewer is a FREE utility to view the contents of OST files. It does not require Outlook installation. A connection with Exchange is also not required. Just select the OST file and it will mount it in its Outlook like GUI instantly. | |
Free tool to convert older *.OST files to *.PST files. Works with ANSI format only, will not work with OST created by Outlook 2003/2007. | |
Exchange OST to PST email conversion tool to convert OST file to PST file. Convert working or unusable OST file to into PST file. Use it to migrates all Outlook items from Exchange Offline Storage (.OST) file to Personal Storage File (.PST). Software converts and repairs the offline storage file (ost) to personal storage (pst) file so that it can be easily accessed with Outlook. Other saving options include .EML and .MSG where former is accessible with Outlook Express and latter with Outlook. If the ost file gets corrupt or damaged, OST to PST functions as ost recovery software. | |
Remo OST to PST Converter is one of the most used tool to convert Outlook OST files to PST files. It helps in managing Outlook data among both IMAP and POP3 account users. Best thing about this tool by Remo is that you an convert a damaged or corrupt OST files into a healthy PST file. This indeed saves you from losing your precious data and then allows you to store it in a more flexible PST file. Remo OST to PST Converter is available to all versions of Microsoft Office and Outlook users, from Outlook 2003 to 2019. | |
Stellar Toolkit for Outlook is a comprehensive software package to manage and optimize Microsoft Outlook profile. Get tools to repair damaged or corrupt PSTs, convert OST to PST, merge Outlook PST files, split or compact large PST files, and more. |
Glenn says
I have 2 email addresses I created a new one, an outlook email address but it shows in a different section in outlook on the left HS the others are at the top the outlook address is at the bottom with it's own links how do I get it up with the others ?
Diane Poremsky says
If you mean the inbox is missing from the Favorites section, right click on the Inbox folder and choose Add to Favorites.
Glenn says
Thanks I think I've solved it but now I have to get the dash thing on my iPhone and I also have Mail Washer got to get it to work in there too.
Just found the confirmation email
KnowItBetter says
It's wrong "If you have an orphaned OST and can't recover the account using System".
Have read so much about that I felt I need to write this to help avoid spending money for nothing:
If you have orphaned OST Files and not bound to Outlook anymore, no big deal - you still can recover and convert them to PST and the best FOR FREE: Mostly no need for such expensive Tools as StellarInfo or CoolUtils whatever –
YOU ONLY NEED OUTLOOK
1. Open Outlook
2. MOSTLY IMPORTANT disable automatic Send/Receive (Outlook may not sync automatically)
3. Create a new dummy-mailbox in outlook that works as a container. We need the container-.OST in a minute as sort of a jar.
4. Open the local folder where this .OST ist stored
5. Close Outlook
6. Now, take your actual .OST File that you need to convert (and which is not in Outlook anymore – if it were you wouldn’t have to do that)
7. Rename your .OST to the container-.OST filename, copy and overwrite the container-OST with yours.
8. Open Outlook
9. Use Import/Export Function and follow the steps to export your dummy-mailbox as PST.
10. Repeat that for all your orphaned OSTs
You even can move those messages to another existing mailbox.
Diane Poremsky says
When I try that, I get this message - "The file ***.ost cannot be accessed because it has been configured for use with a different mailbox."
nszaeye says
Just a clarification, OST files are offline files that you can access your emails without having a direct connection to the exchange server from the last synchronization, that is, outlook accesses your emails since the last synchronization offline (called mode cache). If the emails are deleted from the server, the moment the outlook reconnects to the server, those emails will also be removed from the OST file, so it would not work in a very effective way for security as you are placing.
The way you are trying to work would be via PST files, where it downloads messages to the file from the server, and even if you delete these messages from the server, they will remain in the file in question, so it would serve what you are looking for .
Follow:
https://support.office.com/en-us/article/Introdu%C3%A7%C3%A3o-aos-Arquivos-de-Dados-do-Outlook-pst-e-ost-6d4197ec-1304-4b81-a17d-66d4eef30b78
To export the ost files to pst use GainTools OST to PST converter
Anandita says
Thank you, Diane, for such a useful article page to convert exchange offline ost into Personal files. very useful page on converting OST to PST. I am really amazed to not find SysInfoTools OST to PST Converter as the Featured tools list. Few Months ago, I got the software and installed the demo version with the help of which i was able to convert 25 emails successfully. After this success in conversion, I got hands on the software and purchased it. I am still using the software without an issues.
Name cannot be empty says
I think what most people are complaining about is just that. We are looking for a freeware (not a try before you buy with limited capabilities) version of software. We have gotten used to the internet, software, pirating software and shareware which leads to the mentality that everything should be free.
Diane Poremsky says
Yeah... that is definitely an issue. And the problem with the repair software (and some sync) is that they advertise as Free for consumer or home use, but when you install you find out their idea "free" is not the same as yours - a Free Trial that does 5 messages per folder or 50 total or something similar is one thing, but you can't say that is free for consumers.
Jerry Stinson says
Hello Diane. I have seen your name and some posts on the forum, and thought I would reach out to see if you have any sage advice or counsel for me. I am new to the forum, and not familiar with any protocols here so trust this is satisfactory. Best regards…Jerstin -
I hope you will be able to help me. My wife’s PC (W10 home) was knocked out by a recent Microsoft update, and is caught in a non moving cycle repeating attempts to boot and un do changes without success. I have contacted my local techie support guys, and tried various things but cannot get windows to boot, or repair. It appears that we will have to do a full re-install W10, and despite having back-ups for most documents, have not been able to get Microsoft Office 365 Outlook email contacts and calendar details. Original email account was set up as an IMAP account, and I have pulled and accessed the HDD on a docking device, found the email .ost folder data file , migrated it to another laptop also with Outlook 365, test set up a new email account as an imap account, and after accessing the .ost file. The email shows up, but there is no access to calendar or address book. Big issue for my wife!
I have read about converting/creating a .pst file, with commercial software tools to convert .ost files to .pst file, and claim to resurrect the calendar and address book detail in a .pst file. My question is if that can be done, how would I use the converted .pst file? i.e. a new imap account or a POP3, should I re-establish her email account as a POP account and point it to the converted .pst file in required location…could it be that simple? And, would it likely work?
I have not been able to find any other location, or data files for the calendar or address book details, and if we can resurrect these email details I would be happy to do a clean re-install of W10, and try to get past the current …g..d… install problem. Happy wife, happy house, and her email addresses and calendars are key to that.
Diane Poremsky says
sorry I missed this earlier. :( Did you get it solved?
>>
The email shows up, but there is no access to calendar or address book. Big issue for my wife!
>>
The calendar and contacts in Outlook 2013 and up that are labeled 'this computer only' do not sync anywhere- you need to export them to a CSV file. If you have an older profile with a separate pst for calendar and contacts, you need to make a backup of the pst.
>>
convert .ost files to .pst file, and claim to resurrect the calendar and address book detail in a .pst file. My question is if that can be done, how would I use the converted .pst file?
>>
Open the pst in the profile, set it as the default data file and if the imap account has folders named this computer only (because it was set as default) , rename the imap data file and let outlook resync it.
MrPete says
Kernel successfully read the entire file and built a folder tree.
Positives:
- Apparently, it may be able to retain complete email headers
- It does work
- No charge, it will save up to 25 messages per folder.
Negatives:
- It does not track how many messages are in each folder. You get NO idea how much data has been recovered
- The killer (for now). This software is unbelievably slow even on my crazy fast machine (12 core i7, 32GB RAM, RAID 0 SSD temp drive with 1GB/sec throughput)
-- every cluster of data is read twice in a row. A bug. (Discovered using SysInternals ProcMon)
-- Every recovered item requires REreading a lot of data... ~120MB! All in all, it could read about one item a second. We're talking MANY hours...
That slow speed affects everything:
- Viewing messages in a folder. They show up one.....by............one..........very......slowly. Oh so painful.
- Creating a report to count number of items. I gave up after several hours with no results... it had counted a few thousand.
- Exporting to PST. I gave up after a while.
If necessary I was willing to stay with this one... but it was SO painful.
Next up: Stellar
Stellar was... Stellar. I was relieved. After all, I had been through so many failed packages! (One of the failures was discovered after Stellar. It was my final shot. To complete my list I did test even though I had a good result w/ Stellar.
It read the whole file. It tracked message counts live. It quickly displays any message (no charge.)
Positives:
- It works, and works quickly
- In my scenario it recovered more than 120,000 emails, thousands of contacts and calendar items, and even suggested other contacts.
- It shows how many messages are in each folder, making it simple to see what data is there... or is missing. Any message is easily displayed, including photos etc.
- No charge, it saves up to 20 messages per folder.
Negatives
- Rumor is it doesn't preserve original Internet email headers. I've not checked this yet.
One Confusion
I am a bit confused about messages marked for deletion: Kernel said thousands were marked for deletion, yet it could display them just fine. In Stellar the same weren't deleted. A few other delete markers were found.
MrPete says
Diane, here's a Sep 2018 update.
CONTEXT
A friend had a horrible computer crash involving both internal drive an primary external backup. I did a ton of work (sadly, after a series of dumb techs gave up and overwrote the installed Windows... and most of her files :( ...)... and got supposedly several copies of several OST files. Clearly most were actually bad. In fact, the very best one was still damaged. The files are 18GB and I knew they contain about 100,000 archived emails etc. A good test.
So, my goal was to find an OST to PST converter that would work with a damaged file, and do a good job of recovery, and function WITHOUT having Outlook already setup for the account. (After all, we're in disaster recovery mode. I don't HAVE everything nicely set up :) )
One more context item. MANY here have the wrong idea about OST files. Long ago, they were just a local cache of MS Exchange data. Delete and rebuild from server.
NOT ANYMORE. Today, it is the ONLY (local) archive of IMAP data that you have archived and deleted from the "live" mailbox... and the same with Office 365 email. An OST file can be crucial! (In this case, over 100,000 emails, thousands of contacts, etc... that do not exist anywhere else.)
RESULTS
I downloaded and tried literally every OST to PST software I could find.
All but two would not even get started. They either complained because I don't have the account already setup on Outlook, or they took one look at the file and ran away screaming (virtually) because it has defects. Sigh. Here's are all the failed products:
DataNumen Exchange Recovery v5.5
InFixi OST Converter 2.0.0
Softaken OST File Exporter 2.0
KdeTools OST to PST 2.0
DataInfo Tools OST to PST 7.12 (by Bitintech Software Pvt Ltd)
OST to PST Converter by Software Imperial Pvt Ltd 2.10.0018 / 1.10.1110
4Team OST2 and OST PST Viewer 9.0.21022
Here's who was left. They have significant differences as well:
Kernel for OST to PST 18.1 by Lepide Software Pvt Ltd
Stellar OST to PST 3.0.0.0 by Stellar InfoTech
I'll add my results next... no room :)
Diane Poremsky says
>>
Today, it is the ONLY (local) archive of IMAP data that you have archived and deleted from the "live" mailbox... and the same with Office 365 email. An OST file can be crucial! (In this case, over 100,000 emails, thousands of contacts, etc... that do not exist anywhere else.)
>>
OST are still local copies of the mailbox on the server - the only exception is calendar & contacts in an imap account - if there are calendar & contacts folders labeled 'this computer only'.
if you archived mail and deleted it from the server, it would be in a pst. When its deleted from the server, its deleted from the ost too.
anshul says
you are looking through any PST Repair Tool you will get numerous arrangements. Be that as it may, I prescribe you to utilize Microsoft inbuilt Inbox Repair Tool. With this instrument you initially select the undermined PST record in your framework, at that point check the debased PST document. Once the checking procedure is finished, you can choose the Repair alternative. In the wake of repairing process is finished, you can see the repair PST record.
Diane Poremsky says
Sorry, but the inbox repair tool won't help converting ost files to pst files.
shiv says
To convert OST file to PST file, you can get the help of Kernel for OST to PST Converter software.
RMarie says
Hi Diane - if I try to convert ost file to pst file would my old company know I am accessing my old email files? I have made a copy of my Outlook before I left the company. I just need my personal emails, contacts, calendar.
Diane Poremsky says
No, they will not. Once you left and they disabled your account, they lost the ability to know what you do with anything in the ost.
RMarie says
What is the best free converter for me to use? The ost file is quite big
Diane Poremsky says
There is no free converter - the ones who advertise as "free" will let you view the contents of the ost but only export 5 or 10 messages. Any of the products in Tools in the spotlight (or Featured at the top of the page) will do a good job.
FrancisN says
Hi, I received an MS upgrade on an MS Surface 2 machine. This caused it to crash and my supplier could not restore it to working condition. They were able to copy my files including Outlook messages to a USB stick and I have saved them on a new Surface Pro using Windows 10. I now want to import them to Outlook, but this requires them to .pst files.
I see that these messages are saved as .ost files, something I have never seen before but I am told is used by Exchange - which I have not used on these machines. How do I create a .pst file of these emails, please? There are about 3000 messages and I need very urgent access to them. I need real help from MS who seem to have caused this problem in the first place.
Many thanks and regards,
Francis
Diane Poremsky says
ost files are also used by imap accounts. the mail in them should be in also in the mailbox on the server. you only need them if your calendar and contacts are also in them. If you need to get them out, you'll need to use an ost to pst program.
Wim v,d, Burgt says
I have to convert OST files to PST files, because I want to use some of the folders with mails from the old OST files in my new Office 365 accounts.
I bought the KERNEL OSTPST convertor, but the conversion failed.
It looked like as if KERNEL OSTPST failed working with WINDOWS10.
I tried some of the other conversion tools, but non of these worked as promissed.
Where can I get clear instructions.
Perhaps you could offer me a better alternative?
Diane Poremsky says
It works on windows 10 - I've tested it on it. Did you get any error messages? what happened when you tried it? The usual reason these programs fail is the data file is corrupt.
Cindy B says
Thank you, Diane, for a very useful page on converting OST to PST. You might consider removing Stellar OST to PST Converter from your Featured tools list. I installed the demo and could not "select 20 files from each folder" as they explain for their demo. I initiated a chat and asked about that and had one other question. After 30 minutes, they replied with something akin to "The folders you see are what you get," which, of course, did not answer my question of how to choose 20 files (since using Ctrl and/or Shft didn't work). But I tried again with my 2nd question which was "where is the Inbox folder", they replied with the same answer. I suspect I was speaking to a robot. I went back to their site later (after trying and buying the Kernel product) and, just for grins, I clicked on the Better Business Bureau icon at the bottom of their site. Lo and behold, they are not a member of the BBB.
Catchup says
For the second time in two months, I lost my entire calendar in MS Outlook 2016. At the same time, I have had some Windows 10 (Home) issues, where Windows 10 attempts to update, fails somewhere, and endlessly tries to install updates, then uninstall and then attempts the update again, so I don't know if the two are related. My Office version is 365 Home. When emptying my email inbox trash, my calendar was also wiped entirely clean and all entries in my address book disappeared. The error messages I get when trying to go into address book or calendar are that the requested folders cannot be opened. So, what is the best way to either use or convert an .ost file into usable data? The first time this happened I was somehow able to replace the corrupt/wiped .ost file with an older one from my local backup, but this time I am stuck. Microsoft support does not know how to solve the problem either, the closest we came after 1.5 hrs on the phone was to add a exported backup .pst file (which I had created a month ago) to my local (now completely blank) calendar, so I have most of my calendar entries back in a secondary calendar, but I would love to be able to recover the data from the backed up .ost file to access all calendar entries that were added in the past month. Thanks!
Diane Poremsky says
It sounds like you are using an imap account with your calendar and contacts in folders labeled 'this computer only' - you need to create a pst and set it as the default data file so its used for calendar and contacts. then make sure you back it up before resetting the computer and on a regular schedule.
https://www.slipstick.com/outlook/2013/imap-accounts-outlook-2013/ has more information.
lucy cruz says
good explanation
mulley says
I did my first computer build yesterday and it went very well except for the re-installation of my outlook account. I copied the .pst files to my storage drive because I have several hundred folders with many saved emails plus all my contacts and calendar. When I reinstalled Outlook 2016 last night (same hard drive, with a clean windows install) I went to the folder to open the files I realized that the files were .ost instead of .pst and cannot be opened. I have a .pst file from February that opened fine but that means I have lost 8 months of emails. Any advice on the best way to get the .ost file reopened will be appreciated.
Diane Poremsky says
The ost files are copies of mail in IMAP, Outlook.com, or Exchange server mailboxes. When you add those accounts to your profile, everything on the server will sync down - this should be all of the missing mail.
There is one issue that could result in missing mail - if you moved mail from a pst into the ost file, it's possible some of it did not sync up. If you never imported mail into these accounts, this will not affect you.
mulley says
Thank you, for the quick reply, though I am not sure if I understand everything. My email account is an IMAP through my isp, using Outlook on my computer. Whenever I have reformatted my hard drive I copied the pst file to another drive and then re-opened it when I reinstalled outlook. This time, though the file I saved was an ost file and I did not realize I would not be able to reopen it as I have done before with pst files. I have 107 folders of saved mail that show up on my isp's web mail but they do not show up in outlook now that I have reinstalled it. New emails are coming in but "sent" mail and all my folders are missing and I have no idea how to get it all back.
Diane Poremsky says
they changed how imap worked in outlook 2013... all of the mail in folders in the imap data file should sync back to the server. if they weren't and you didn't export to a pst, they are not recoverable. if you had 2 data files in your old profile its possible the missing mail was moved to a pst... but if you didn't save a copy, it is not recoverable.
if the folders are not on the server, i can only guess they were in a separate pst. Default location is typically in my documents\outlook files - if you backed up the entire documents folders, you might have a pst, if one existed.
if you used calendar & contacts, they are not recoverable if you kept them in folders labeled 'this computer only'. if they were in a .pst file, you need a copy of that pst.
sankony says
Which tool best you are mention 4 to 5 company.
Diane Poremsky says
Any of the featured products should work fine for any size company, large or small.
Sam says
Hi, I am using IMAP protocol for my mailbox and want to automatically .pst files in my local hard drive. Is it possible ? If it is, please suggest me the way, How i can do this. Any help much appreciated !...
Diane Poremsky says
if you use outlook 2010 and older, the imap pst file can be copied to make a backup. it can be opened in any outlook profile. The ost file used by outlook 2013 and up can only be opened by the account that created it. Because it can't b accessed if the account is deleted from the profile or on another computer, a copy is less than useful. Because imap mail is stored on the server, you really don't need a backup.
Sam says
Thanks for your reply, but I want to keep my all data (all emails, Calander, and contacts) backup on my local hard drive, which seem tricky with IMAP protocols. Is there any possibility to make an all data backup with IMAP protocol ?
Diane Poremsky says
using 2013 and 2016, backing up the imap data file won't help you. You need to export it. If you use the 'this computer only' folders created in a n imap ost when its set as default, you need to back them up.
Novice says
I am changing employers to a related organisation within government sector and need to take my old Outlook 2010 emails with me - about 30GB of data. IT staff have saved all my old emails to an offline .ost file but I can't import this to new Outlook. What is the best tool/method for me to use so I can access these old emails? Any help much appreciated!
Diane Poremsky says
You can't use an ost - the mail needs to be exported to a pst. Do you still have access to the old account? if so export it to a pst. if not, and the only thing you have is an ost file, you'll need to use one of the commercial utilities on this page.
JoeB says
Hi,
I was wondering if anyone had any experience in using any of the utilities to convert from an OST directly into an Exchange Server. I see that Kernel does offer that as a feature. We have an Exchange server but back in December we had some major network/connectivity issues and moved to a hosted exchange server. now that the crisis with the network is over, the owner of the company wants to move back to our own exchange server. It was a nightmare getting our mailboxes exported to PSTs and then having the outside company import them. Now we are moving back I was hoping I could do it all in house by taking the OST for a date range and importing the data back into the existing mailboxes directly. Any comments would be great.
JoeB
Diane Poremsky says
How many users? if you have many users, there are 3rd party migration utilities that would be cost effective.
JoeB says
We have about 100 mailboxes.
Diane Poremsky says
Definitely faster with a 3rd party utility.
JoeB says
do you mean 3rd party utilities other than Kernal OST to PST. From the description, the corporate version can go from OST to Exchange directly? Are you familiar with the product, if not do you have any suggestions based on some experience with the products?
Diane Poremsky says
I meant a utility in general - there are utilities specifically for migrating from one server to another too.
https://www.slipstick.com/addins/exchange-server-migration-tools/
I haven't used kernel's ost to pst in a few years so things may have changed, but I think it goes to exchange through outlook. It should have a free trial available so you can test it see exactly how it works.
Kiran says
Any freeware software to convert ost to pst?
Diane Poremsky says
No, not for Unicode format. The only known freeware only works with the old (pre-Outlook 2003) ANSI format.
Musi says
Hi Diane
I really need your help and I appreciate if you could possibly guide me as this is vital for me
Regards
Diane Poremsky says
I'm not sure how i can help - if you need to convert an exchange ost to a pst and can't use one of the methods in the article, you need to use a 3rd party utility. Any one of the 3 featured products should work just fine. They have trials so you can see if the program can open the ost before purchasing.
Brit says
Buyers Beware:
I archived my whole company to PST using this tool, and had it imported into a 3rd party online archive. After doing this, users would find no results using To or From -- but doing a basic text search of the address would find results.
I investigated this an determined that the Stellar EDB to PST does not actually keep the original format intact in the PST, despite this info on their web page:
"Converts MS Exchange database files (EDB) into corresponding PST files and extracts all your mail components with their original format absolutely intact"
The issue is that this converter does NOT bring over the true header information (what is seen if you crack open the email and look at the source). This is a problem for indexing systems that rely on the actual data and not what is displayed in the From/To/Subject part of an email.
You can verify this by looking at the properties an email from your inbox, then look at the same properties of the same email after extracting it using Stellar.
I requested a refund as I will have to purchase another OST to PST tool (Lepitde OST to PST Converter), which does the job correctly and DOES carry over all of the original forma absolutely intact, but was denied.
So if you are using this in an enterprise environment and need that information, Stellar will not provide that. Otherwise the product is fine, but for me, it makes it useless.
Theodore Weitz says
Hi Diane --
This is a very helpful site. I recently had my computer in for repair and when they did a system refresh, it preserved my document file, but a large critical file is now shown as an .ost when I search in the "windows.old" files that were created. Since I did not have an exchange server, I can't figure out why this happened, but I need to recover the valuable information it contained. I am using the Microsoft office 2013 software, and was wondering if the tools you described will all work with Office 2013. I know that previous versions monkeyed enough with the fle structure that what works with one does not necessarily work with the next version.
Diane Poremsky says
I'm guessing it was an imap data file - the messages in it should be on the server but if you had contacts and appointments in the 'this computer only' folders, they would be in the ost. The last time I tried, the recovery tools did not work with the imap ost files, but it's worth trying (because restoring the old windows is a pita) You could try using a pst repair tool too.
John says
Use Mailstore Home (free for personal use!). If you have your emails via Exchange then just select Microsoft Outlook from the menu. You can also configure access to email server via manual settings.
Glen Wenzel says
Hi Diane, Thank you so much for your quick reply and the valuable information about the PST data files and their sizes. Knowing that the 2 GB limit is no longer a concern, is extremely useful and means I will not have to keep monitoring them as I've been doing up till now. Plus, I know now that creating a backup copy of the OST file will not be a problem due to its large size.
Please know how much your expert assistance is appreciated. Thanks again.
Glen W.
Glen Wenzel says
Hi Diane, I am thinking of using the OST2 program to convert a large OST file into a PST. However, the OST file is 6.7 GB in size. Is there not a limit of roughly 2 GB on the size of a PST file, after which Microsoft says it cannot guarantee the PST file's stability ? (The OST file is from Outlook 2010.)
Also, am I correct in thinking that the converted PST file would be roughly the same size as the OST file ?
Thanks for a great article. It is VERY helpful !!
Glen W.
Diane Poremsky says
The (new as of outlook 2003) Unicode pst format is unlimited so it should work fine.
As for pst/ost size comparisons - it's really difficult to know but it will likely be close to the same size. The converted pst might be as much as 25% larger (messages in pst file can be larger because of the way Exchange stores messages) - it might be a smaller if there is a lot of "white space" that wasn't compacted. Because outlook doesn't compact until there is 20% white space and the computer is idle, there is a theoretical 1.20+GB of white space in the ost. The larger messages in a pst and white space in the ost can cancel each other out.
Karry G. says
No problem Diane! I've done ost pst conversion with Stellar tool. BTW, you're doing such a fantastic job through your blog.
And, thanks again for your valuable fast response!
Karry G.,
Karry G. says
Dear Diane. As per your software suggestion I tried stellar ost pst converter for Outlook file conversion. Of-course it worked fine, but can you recommend any free ost to pst converter too!
Looking for your response!
Karry G.,
Diane Poremsky says
There aren't any free tools that work with the Unicode file format. Sorry.
Chris says
Does anyone know of a version of .OST to .PST conversion software for a Mac?
Diane Poremsky says
Sorry, I'm not aware of any because Mac clients don't use ost files (and don't use pst, but they can import pst files).
Wes T says
The computer used by our senior project manager locked up and was then powered down hard. When the user rebooted and returned to Outlook 2010, all mailbox contents were gone. On the exchange server 2003 System Manager this user's mailbox still contained the same amount of data as it had pre-crash, but we could not gain access to it in Outlook or OWA- somehow it was corrupted during the power down. After Googling this problem I ended up reading your article. I decided to purchase the Stellar Phoenix software which was less than $200. The online purchase and license delivery for Stellar Phoenix seemed rudimentary and made me a bit nervous that I was about to be scammed, however, the end result was perfect. I extracted the .OST file from my user's local hard drive and allowed Stellar Phoenix to chew away at it overnight. The output was a large .PST file containing ALL of the user's lost mailbox contents. The PST opened perfectly in Outlook 2010 and even the structure of inbox sub folders rendered correctly. What a huge relief! As this user was mid-project on several multi-million dollar stadium assignments, this was $200 I was glad to spend! Now if only there was a way to purge the old "corrupted" data which is still lurking somewhere in the user's exchange mailbox... Thanks for the helpful article!
Brian Diana says
HI Diane I have noted more and more of the office 2013 email addresses are being setup at ots even if they not exchange addresses
Diane Poremsky says
Yes, any account type they syncs to the server now uses an ost file. That would be IMAP and Outlook.com (Hotmail), with only POP3 and user-created date files using pst.
IMHO the only problem with this is with IMAP - if the user decides to keep calendar and contacts in the IMAP ost, they need to export the 'this computer only' folders to make backups, not the entire data file.
Clippingimages says
Awesome post! I will keep an on eye on your blog.
Dinjy says
thanks a lot
Garrett says
Thanks for this list, Diane. It's a great cross-section of tools for viewing ost files and for the benefit of IT support or sys admin's to maintain and service their users' accounts. However, I'm a new hire with legacy data trapped in an ost from a previous employer. It is all I could export from there before leaving and therefore without a translation into an actual pst file it's practically useless. Without the ability to use the attachments and extract email addresses, contacts, etc., it's more of an inconvenience than productive. Is there a software product that will allow me to not just view the ost but actually translate it into a pst file that I can add as an Outlook data file? I understand that developers want and deserve to make money from their efforts. But spending $50-$200 to carry my legacy email into my new job once just isn't worth it for me. Do you know of a program that would allow me to get a pst file just once? Thanks,
Diane Poremsky says
Did you try OST2 PST Converter for Outlook? That is supposed to be free. Otherwise, if you have a Unicode ost, you'll need to pay to have it converted to a pst if you need to convert it.
Mark Smith says
What a great list! thank you!
Floyd Shiffman says
Hi Diane, I saw a post below that you responded to to help someone who deleted a exchange acct. and I made the mistake of deleting two of my non active email accounts on my Iphone which then deleted them off my laptop with all my contacts. I tried the system restore but it didn't bring anything back on those email accts? Can you please help me out?
What type of account did you delete? If exchange server, see https://www.slipstick.com/problems/ost2pst.asp
How long ago did you remove the account? If recent, you can use system restore to get it back.
Diane Poremsky [MVP - Outlook]
Outlook Daily Tips | Outlook & Exchange Solutions Center
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Diane Poremsky says
Deleting accounts from an iphone should not delete them from the laptop. Deleting the contacts from *within* an account on the iPhone will delete them from Outlook or your mailbox. Check the Deleted items folder and recover deleted items command to see if you can find them, if not, you will need to have your mailbox restored. System restore won't work because the iphone deleted them from the Exchange server- the only way to recover them if they are not in deleted items or deleted items recovery is by recovering the mailbox from backup. Sorry.
Now, if you happened to have a second profile set up with this account that has not been used since you deleted from iphone, disconnect that computer from the network (so outlook can't sync) and open Outlook to the profile then export the contacts. Go online and import them.
Max C says
Great tips - thanks!
Diane Poremsky says
Thanks for the review!
>>
4Team OST2 turns out to cost $80; the free version is useless, since it will only output the first five records.
>>
This isnt new and it annoys me that they refer to it as Free.
MrBurns says
The DataNumen Exchange Recovery installation on my system was blocked by WebRoot which reported it contains W32.Downloader.Gen malware in the DEXR.DLL.
As they say you get what you pay for and if it is free then you pay for it in some other way.
Joris Linssen says
It appears that Recoveryfix is no longer maintained. I bought the paid version, but it failed to start on my Windows 11 PC. I sent an e-mail to support, but got no reply. Fortunately, the payment provider (MyCommerce) provided a full refund.
Diane Poremsky says
While it is possible that it is infected - many of the recovery utilities will trigger a false positive because of what they do (read /export emails). Unfortunately, I don't know if this a false positive or infected. :(
Diane Poremsky says
Thanks for the information.