Changed thread title to better match contents.
Heya, KKLR. Welcome to TSDN!
You cannot run PHP scripts from an email in Outlook. PHP is a server-side scripting language that uses browser requests as parameters for script execution.
Since emails are at best static copies of web pages, there is no server interaction, and so you cannot run PHP scripts that way.
You can include a link in the email to a web page that will run your PHP script, but you might just want to look at your Outlook settings...
... because Outlook automatically saves your sent emails.