Problem With Mail



How can it be so hard to send mail from one computer to another? I've been racking my brains out on this one for months and I still don't get anywhere. Is it in the php.ini file to change or what. Okay, this is what I have:
This is the article I've used and I rather enjoy it. Here is the link for it:
When I run it as it says, guess what I get an email from it. I'm tickle pink and that is why I like it. This is telling me that hey I can send mail out. But when I download one of these contact forms, guess what? Two possible outcome's, can you guess what happens in my? There is no mail setting on the other side waiting for me to party on with. It doesn't matter which contact form I choose, it's the same results.
So if someone has a heart to help me get though this please let them speak now. Yes, I'm very wet behind the ears to this debian stuff. I'm working on a pi model 4 with 8 gb's of ram trying to host a very simple web site, but I need a contact form to do it.
Thank you for your time