How I may export certain emails from one PST to another?

[Britanica]

My Outlook Email PST has 15 years worth of emails which I have stored in a PST I want to be able to import emails from certain individuals or emails with a specific subject into a new outlook account – leaving all the rest behind in the archive / PST. Is there a tool to make that happen easily ?

[IT-Guy]

You do not need any tools for this, everything is already available in Outlook. You may create rules which will copy emails from certain people and with specific words in subject to the selected folder in your new account. After that you may run this rule for the emails which are already exists. It is very simple, read more in this article, it is well describing how to create and use Outlook rules and allerts. Please let me know if you need the exact step-by-step guide, I may write it for you