What's wrong with this code: $headers .= "From: ". $email. "\r\n";?

Question

PHP

Hello!
The site has a feedback form.
Maybe I'm stupid, but I don't see the error at close range... The PHP script worked fine for two years, no one touched anything, and suddenly it stopped working.
***
Here is the top part of the script:
$to = "[email protected]";
$email = $_POST['email'];
$name = $_POST['name'];
$phone = $_POST['phone'];
$msg = $_POST['message'];
$subject = "Request from our site";
$headers = "MIME-Version: 1.0\r\n";

Answer 1

You cannot use other people's e-mail addresses in From, this violates DMARC and for domains with a strict DMARC policy (mail.ru, yahoo.com) letters will not reach. Put in From and envelope the addresses that your server is authorized to send, set up SPF and DKIM for the bottom. If you need to reply to letters, then put the user's address in the Reply-To.

Answer 2

The order is also important. Before the mail() function, print all its arguments and you will see an error.