How to Auto-Archive Outlook emails

To significantly reduce the size of the Outlook data file (PST), you can use the auto-archive feature. This feature allows you to automatically move or delete old emails from your Outlook mailbox, thereby reducing the PST file size and enhancing its performance.
Here are the step-by-step instructions to do it:

Step 1: Open Outlook and navigate to File > Options.

Step 2: In this window, open Advanced and go to AutoArchive Settings.

Step 3: Choose Run AutoArchive every to specify frequency of archiving your mailbox items to the selected archive location.
(The default archiving period is 14 days.)

Now, click OK and restart Outlook to allow the changes to take effect.

Credit : https://www.stellarinfo.com/blog/fixed-outlook-is-running-slow-on-windows-10-11/