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ost file too large

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ost file too large - 21.Nov.2006 5:03:19 AM   


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Currently our ost is only able to store 1.9gb. How do I make it to be unicode so that it can be larger. My users are having problem sending out mail.

Please help
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RE: ost file too large - 21.Nov.2006 8:18:16 AM   


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Try this...

How to configure the size limit for both (.pst) and (.ost) files in Outlook 2003


(in reply to harrypmf)
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RE: ost file too large - 22.Nov.2006 1:42:37 AM   


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hi rex2002, thanks for the help. Actually I did try that before.....but when i reach the Policies, Microsoft part.....I can't find office.....weird?

(in reply to rex2002)
Post #: 3
RE: ost file too large - 22.Nov.2006 7:58:26 AM   


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Are you using Office 2003 or other version ?

Using OST or PST ?

(in reply to harrypmf)
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RE: ost file too large - 22.Nov.2006 10:25:50 PM   


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I am using 2003 SP2. Actually I read thru the internet, it says 2003 should be using unicode format ost, but why do I still only able to hit 2gb?

How exactly to check whether i m using unicode or ansi format of ost?

(in reply to rex2002)
Post #: 5
RE: ost file too large - 22.Nov.2006 10:45:00 PM   


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Were these clients upgraded from 2000 who already had existing ost files? You can't upgrade from ansi to unicode.

Setting Up Outlook 2003 Cached Exchange Mode Accounts


James Chong
MCSE | M+, S+, MCTS, Security+

(in reply to harrypmf)
Post #: 6
RE: ost file too large - 22.Nov.2006 11:00:14 PM   


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I think you bring up a very good point. I will try to uninstall the affected pc and reinstall with office 2003. Let's see if it can exceed 2gb. Thanks for the help!!

(in reply to jchong)
Post #: 7
RE: ost file too large - 25.Apr.2007 5:59:27 AM   


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I've got exactly the same problem. I've installed a new Exchange server (Exchange 2003) and migrated the accounts from our old Exchange server with exmerge. No problem so far - even though there was one mailbox with > 3 gbyte.

When I deleted the old mail account in Outlook and added a new mailbox, the data replication stops when the ost-file is about 2 gbyte. Now comes the funny part: The same outlook accepted the "old" mailbox with its > 3 gbyte. There were no changes in the outlook configuration etc. Furthermore, I tried to replicate the "new" mailbox on a laptop (which was former used to replicate the "old" mailbox with its 3 gbytes- with no problems) and got the same error.

All in all, I think that there is a problem with the exchange configuration, but
a) I haven't configured anything about mailbox size etc.
b) Using OWA, there is no problem to access the new mailbox with its 3 gbyte
c) There was no error when I copied the 3 gbyte mailbox to the new server with exmerge

I tried to change the ost-size as it is described in http://support.microsoft.com/kb/832925, but when it comes to HKEY_CURRENT_USER\Software\Policies\Microsoft\Office, there is just no Directory \11.0\Outlook (we are using Outlook 2003) and accordingly no registry key.

I would be very happy if anybody could help me with this problem.

< Message edited by Duschwolf -- 25.Apr.2007 6:01:35 AM >

(in reply to harrypmf)
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RE: ost file too large - 29.Oct.2010 5:39:02 AM   
Jim Chou


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On outlook before 2003, over 2GB ost and pst won't be accepted.
After outlook 2003, it's dealt but as the ost gets larger, operations could be slower.
Try Advanced Exchange Recovery. It can deal with this problem and convert ost 2 pst.


(in reply to Duschwolf)
Post #: 9
RE: ost file too large - 13.Jan.2011 6:05:32 AM   


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r u using office 2003 or 2007
If the file system on ur computer is FAT convert it to NTFFS file system and check

(in reply to hohelpoutlook)
Post #: 10
RE: Outlook OST to PST **** - 24.May2012 6:15:17 AM   


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When an Outlook .ost file reaches or exceeds to its limit, you may face any one of the following problem:

- Fails to open or load the OST file data.
- Cannot add any new items to the Outlook .ost file.
- Synchronization problem with the Exchange server.

To work around this problem, try to delete some old or unuseful items from your mailbox. If you are unable to access your .ost file due to the corruption, then you need to repair and recover data from this damaged .ost file by converting it into .pst file. Here is a one of the few tips to convert ost to pst application:http://convert-ost-pst.blogspot.in/

This features rich tool has a very simple and easy to navigate user interface which will help you to save time. Free demo version is also available over the internet.

< Message edited by nelson -- 24.May2012 6:32:50 AM >


Brian Nelson
Outlook PST Repair

(in reply to Radiomedia2)
Post #: 11
RE: ost file too large - 1.Aug.2013 2:21:27 AM   


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To configure OST or PST File size use Registry entries which will help you into configuration of OST file size or PST file size if it exceeds from their limit i.e. 2gb.
Read the following blog article

< Message edited by ostrecovery -- 1.Aug.2013 2:23:11 AM >

(in reply to harrypmf)
Post #: 12
RE: ost file too large - 20.Jan.2015 2:26:05 AM   


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Follow the following steps provided by Microsoft to reduce the size of OST file: -



(in reply to harrypmf)
Post #: 13
RE: ost file too large - 2.Mar.2015 5:28:44 AM   


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Thanks for all sharing such a useful information. I also want to share one more thing that for repairing OST file error. Users must use OST to PST **** Software which has a good reputation in the online market. And its full version does not cost so much.

Visit its official web-site: http://www.osttopsttools.com/

(in reply to harrypmf)
Post #: 14
RE: ost file too large - 17.Feb.2016 1:03:03 AM   


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The ost file format is very complex. It starts with a file header containing the meta information of the whole file, followed by several parts containing the actual data. You can find more detailed information about the ost file format by searching on Google with the keyword “ost file format”. If the file header containing the meta information is corrupt, or any follow-up parts are damaged or corrupted, then you will not be able to open the file correctly with Ms Exchange. In such a case, the first step is to try to use the built-in repair or recovery function in the Ms Exchange, to see if it can repair or recover the corrupt file. If not, then you need to resort to a third-party ost recovery software to scan the corrupted file and retrieve all recoverable data for you. It is also possible to find a data recovery expert or company to do the task, but in most of the cases, they will also use a third-party tool to do the recovery for you.

There are several methods to convert OST file to PST file.

First, Microsoft does not provide an official tool to do the conversion. However, if you can access the contents of the OST file in your Outlook, then you can perform the conversion manually, as follows:

1. Start Outlook. Make sure you can access all the contents in the OST file to be converted.
2. Create a new PST file.
3. Go to the OST file, select and copy all the contents to be converted with your mouse.
4. Go back to the new PST file, then paste all the contents into the PST file

That will do the conversion.

You can also perform the conversion by export the contents of the OST file to a PST file by following the instructions at:


Second, if you can access the Exchange server containing the account data for the OST file, then you can use Export-Mailbox command to export the data into a PST file, similar to convert your OST file into a PST file. Below is the article about doing that:


Third, if you cannot access the OST file via Outlook, neither can you access the Exchange Server, there are many third-party OST to PST conversion tools you can try, below is a list of them:


Nearly all these tools provide a free trial so you can try first to see if a tool works before purchase it.

The main difference between using the software by yourself and by a third-party service company is:
(1) The company is familiar with the data recovery industry so he knows which software is the best one. While you need to search and compare the software online by yourself, which is time-consuming.
(2) The company purchases the software for multiple usages, while you purchase the software for one-time usage only. So normally the service fee may be cheaper than the license fee for the software.
(3) DIY will keep your data confidential while do the recovery via a company may cause data breach.

Hope this will help

Good luck!

< Message edited by zara8942 -- 5.Apr.2017 1:16:15 AM >

(in reply to harrypmf)
Post #: 15
RE: ost file too large - 18.Feb.2016 4:43:04 AM   


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I have used a Good OST to PST convertar software Solution to completely repair corrupt .ost fiels and successfully saved/convert into Outlook .PST files formats without facing any error.

For download - http://tinyurl.com/jdo7mma

(in reply to zara8942)
Post #: 16

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