Hi All,

We seem to have an issue were user's .ost files keep growing into GB in size however the mailboxes are all restricted to a 200mb limit can you please advise thanks

Firstly, I would explain why the local OST is larger than the size of mailbox generally. The reason includes as the following but not limited.

1) Some update changes some of the storage algorithms in favor of better performance which adds ~20% free space to OSTs.
2) Exchange mailbox data is compressed on the server but not in the OST.
3) OST stores a good bit of metadata that either isnt present on the server or not listed in the size comparison. Im not sure what the ratio is offhand however.
4) Any sync issues in the sync issues folder are local to the OST and are not on the server, as are those in conflicts/local failures.

5) Share folder and public folder are also downloaded.

At this point, we may consider to reduce the size of Outlook data files in Outlook 2010

http://office.microsoft.com/en-us/outlook-help/reduce-the-size-of-outlook-data-files-pst-and-ost-HA010356311.aspx 

More infomation:

http://support.microsoft.com/kb/982577/en-us

Cheers,
Tony Chen
Forum Support
________________________________________
Come back and mark the replies as answers if they help and unmark them if they provide no help.
If you have any feedback on our support, please contact  tnmff@microsoft.com.

• Edited by Tony Chen CHNMicrosoft contingent staff, Moderator Sunday, September 15, 2013 4:37 PM
• Marked as answer by Signumxsa Monday, September 16, 2013 11:32 AM

Thanks Tony issue appeared to be downloading shared folders

Hii,

MS Outlook File grows as you create and receive items. Sometimes user of MS outlook encounter an error that OST file exceeded its default maximum file size while sending and receiving emails. Deleting some data item from OST file might not decrease the file size in proportion to the data that you deleted. 

To reduce the size of ost file you can either use Synchronization Filter method or you can compact the size of ost file on advanced tab settings of exchange account. Synchronization filter Method restricts particular data items to be synchronized from exchange mailbox to ost thereby reducing the size of ost file at some extent.

Steps to be followed for Synchronization filter method,

• Right click on folder and click properties
• Click synchronization tab and then click Filter
• Now provide the appropriate criteria for filtering that you want according to what data items should arrive in folder.
• Click Ok and open outlook now