On the taskbar, click the File tab> Information> Account Settings. In the Account Settings dialog box, click the Data Files tab and select the Outlook data file you want to compress. Now click on “Settings”. In the Outlook Data File dialog box, click the Compress Now button to compress the PST file.
Outlook users are mainly concerned with limiting the size of PST files. If it’s ANSI PST, you cannot store more than 2GB of data. On the other hand, Unicode PST can store data between 20GB and 50GB. If the PST file is large, it can cause performance issues. However, if it exceeds the size limit, it may be damaged. In such a situation, you can use the built-in lightweight feature of the Outlook client to compress PST files without any modification. There is another way to reduce the size of your PST file, which is a professional PST compression tool.
A PST file or Personal Storage Table is an Outlook data file that stores all the items in your Outlook mailbox, such as email, contacts, calendar, appointments, tasks, mailing lists, and more. Your mailbox size MS Outlook grows as you create and receive articles. Removing some items from your Outlook mailbox may not reduce the size. All deleted items are moved to the Deleted Items folder. Thus, they will always be in fa le. Due to the size limitation of PST files, the Outlook data file cannot store more data than this limitation.
“>2. Erase Everything You Can
This step is pretty straightforward: remove whatever you can.
Keep in mind that when you delete an item in Outlook, it simply moves to the Deleted Items folder. It will not make space until you clear it. So, right-click the Deleted Items folder and select an empty folder to permanently delete its contents. This frees up the space occupied by the deleted items.
However, this does not immediately cause the file to collapse. More details below.
Fix The Broken PST File With Scanpst.exe
If the PST file is corrupted, you can use scanpst.exe to check for errors and fix them.
The location of scanpst.exe depends on your version of Outlook. Learn more about the location of the scanpst.exe file for your version of Outlook and how to use the file For PST, see Using the Inbox Repair Tool (scanpst.exe)