Reduce Size Of Pst File. When deleting a large number of Outlook items from a pst file and emptying the deleted items folder many users expect to see the pst file size reflect the changes immediately. To ideally stop the disastrous events we can put worthy efforts to keep a check on PST file sizes and compress the PST file if required.

Utilize Outlook Compact Functionality. Reduce the size of Outlook Data File pst If you delete items in Outlook Data File pst the files will automatically be compressed on the background when Outlook is running but you are not using the computer. Now click on the Setting and opt Compact Now option to move forward.
Start Outlook 2010 or later with a profile that contains your originalpst file that is larger than 20 GB.
In the Account Settings window click the tab for Data Files double-click the PST file click the button to Compact Now and wait for. Right clicking on Personal Folders shows the size of the Outlookpst file at 37 GB. Using the Outlook Backup Tool the backup folder. In the Account Settings window click the tab for Data Files double-click the PST file click the button to Compact Now and wait for.