Are you unable to synchronize your OST (Offline Storage Table) file with Microsoft Exchange Server? Is your OST file exceeding 2 GB size limit? In Microsoft Outlook 2002 and earlier versions, there is a 2 GB size limit for the OST file. If the file exceeds this size limit, it may get damaged or may not get synchronized with Exchange Server mailbox. Thus, it may not be possible for you to convert your OST file to a PST (Personal Storage Table) file. This prevents the OST file from being updated. To connect with Exchange Server in such a case, you need to manually Convert OST to PST.
When you attempt to synchronize the OST file, which is larger than 2 GB in size, with Exchange Server mailbox, the OST file will not accept more data and you encounter the below error message:
Errors in background synchronization.
In most cases, more information is available in a synchronization log in the
Deleted Items folder.
Furthermore, the following entries are logged in the synchronization log of Microsoft Outlook Express, which is located in the Deleted Items folder:
15:19:28 Synchronizing Mailbox '<username>'
15:19:28 Synchronizing Folder 'Outlook Security Settings'
15:19:28 Error synchronizing folder
15:19:28 The OST has reached its maximum size. To reduce the amount of data in this OST,
start Outlook in offline mode, select some items that you no longer need, permanently
(press SHIFT + DEL) delete them, then re-sync this folder.
After the above behavior of Microsoft Outlook, synchronization and OST to PST conversion processes are terminated.
Grounds of the problem:
The OST files are limited to 2 GB in size in Microsoft Outlook 2002 and earlier versions. When you attempt to add more data to the file, it may get damaged and become completely unusable.
To sort out this problem, you need to reduce the size of OST file and repair the file if it is damaged. You can reduce the file size by deleting unused items from the file and then compacting it.
When all else fails you might need to use a third-party product. One such product is Stellar Phoenix Mailbox Exchange Desktop. The application is particularly designed to effectively Convert OST file
and all its objects to PST. After conversion, you can directly attach the resulted PST file to Exchange Server mailbox and update it.
Further reading from Microsoft : http://office.microsoft.com/en-us/outlook-help/scan-and-repair-corrupted-outlook-data-files-HA010075831.aspx
For more discussion about related problems you can read my blog at http://www.ostpstconverter.blogspot.com
The author is either working for the company providing the tool discussed above or somehow associated with the company.