How to reduce size of large OST file ?

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.

 The default maximum file size (OST/PST) of various outlook versions is: 

•    Outlook 2002 and earlier versions : 2 GB
•    Outlook 2003 and 2007  : 20 GB
•       Outlook 2010 and above : 50 GB

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 should use Synchronization Filter method and then go for Compact now option on advanced tab settings of exchange account.  

Synchronization filter method 

When you are using exchange server account and selected ‘cached exchange mode’ all data items of your exchange mailbox get cached in OST file in your system. Thereby OST file increases in size as the data cached is increased, you can filter the data coming from exchange mailbox using synchronization filter. Synchronization filter Method restricts particular data items to be synchronized from exchange mailbox to ost there by reducing the size of ost file at some extent. Using this method you are able to cache the data items that are received last month, year or on particular date. 

Steps to be followed for Synchronization filter method, 

Step 1: Right click on folder and click properties 
Step 2: Click synchronization tab and then click Filter 

Step 3: Now provide the appropriate criteria for filtering that you want according to what data items should arrive in folder. For examples

       Filter method for mail folder, Select advanced tab and enter these values

       Field: received

       Condition: on or after

       Value: 1 year ago

You can do the same procedure for calendar and public folders

Step 4: Click Ok and Restart outlook now. 

Compact Now method 

After performing Synchronization filter method you can further reduce ost file size using compact now option.  As MS outlook not directly reduce the size of ost file when you delete the data item from it but it can shrink ost file after a particular threshold reached instead of waiting for this threshold you can manually perform compact process using Compact Now.

Steps to be followed for Compact Now method;

Step 1: Open control panel and click on mail 

Step 2: Then select data file in mail setup wizard 

Step 3: Select the ost that you want to shrink and click on settings

Step 4: Microsoft Exchange setting wizard will open here select advanced tab and then select outlook data file setting. 

Step 5: Browse and locate the ost then click compact Now.