Wordpress submit external file

Question

PHP

Hello.
Wordpress question.
I created my own theme and in the page editor I registered a form that submits to an external file that is also in the theme

<form method="POST"  action="/wp-content/themes/site/mail.php">

but when submitting to this file, it gives me that there is no such file on the server

The requested URL /wp-content/themes/site/mail.php was not found on this server.

How can I fix this problem?
Thank you!

Answer 1

If it says it doesn't exist, then it doesn't exist.
You need to write like this:
And in general it is necessary to use actions.