How to correctly configure the sending of mail messages from the server?

Question

PHP

On two different free servers I use the same php code to send data from the contact form:

<meta http-equiv='refresh' content='3; url=http://xxx.com/'>
<meta charset="utf-8">
<?php
if (isset($_POST['name'])) {$name = $_POST['name']; if ($name == '') {unset($name);}}
if (isset($_POST['phone'])) {$phone = $_POST['phone']; if ($phone == '') {unset($phone);}}
 
if (isset($name) && isset($phone)){
 
$address = "[email protected]";
$mes = "Имя: $name \n Телефон: $phone";
$send = mail ($address,$mes,"Content-type:text/plain; charset = UTF-8\r\nFrom:$name");
if ($send == 'true')
{echo "Сообщение отправлено, через 3 секунд Вы будете направлены на главную страницу, где сможете продолжить чтение <a href='http://xxx.com/'>xxx</a>";}
else {echo "Ошибка, сообщение не отправлено!";}
 
}
else
{
echo "Вы заполнили не все поля, необходимо вернуться назад!";
}
?>

From one server, messages come to the specified mailing address, but not from the other. Why is that?
Please also tell me if this code is correct.

Answer 1

if postfix is ​​not configured on the server, nothing will come. Or it will go to spam as a letter sent from an untrusted server. If you want reliability, look for an SMTP provider.
And yes, use ready-made solutions, ala swiftmailer. Always use something ready-made for mail. There will be fewer problems.