Email form problems


#1

I would like to figure out how I could make a form using HTML/PHP/JS WITHOUT having to automatically open the default mail app
I am aware that you can not send an email automatically using HTML or JS, and I am currently unable to find any resources to help me with this
Can someone help me?
This is pretty important, I am making a website for someone and they insist on having an email form


#2

SERP: https://www.startpage.com/do/dsearch?query=php+formmail