If you try to synchronize an .ost file from a mailbox that is larger than 2 GB, the .ost file stops accepting data, and you may receive the following error message:
Offline files (.ost) are limited to approximately 2GB in size. The is the same limitation as a personal folders (.pst) file. If you try to add data to an .ost file or a .pst file that is at its size limit, you receive the following error message:
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.
15:19:28 Microsoft Exchange Server Information Store
15:19:28 For more information on this failure, click the URL below:
15:19:28 Synchronizing Views
15:19:29 Microsoft Exchange offline address book
15:19:29 Download successful
Note Microsoft Office Outlook 2007 and Microsoft Office Outlook 2003 can use a new Unicode file format that can exceed this 2 GB limit. For more information about Outlook data file formats, click the following article number to view the article in the Microsoft Knowledge Base:
Article ID: 288283 - Last Review: Jan 24, 2007 - Revision: 1