Why is the POST request taking so long?

Question

linux

The usual script for sending an email.

<?php
   $back = "<p><a href=\"javascript: history.back()\">Вернуться назад</a></p>";
   if(!empty($_POST['name']) and !empty($_POST['phone'])){
      $name = trim(strip_tags($_POST['name']));
      $phone = trim(strip_tags($_POST['phone']));
      mail('[email protected]', 'Письмо с адрес_вашего_сайта',$name, $phone,"Content-type:text/html;charset=utf-8");
      echo "Ваше сообщение успешно отправлено!<br>Вы получите ответ в ближайшее время<br>$back";
      exit;
   }
   else {
      echo "Для отправки сообщения заполните все поля! $back";
      exit;
   }
?>

It takes a very long time (1 minute 16 seconds 04 milliseconds) to go to LAN.
I just can not understand what is the reason and where to dig.

Answer 1

So the mail function is running for a long time, what local server / assembly Denwer, OpenServer do you have, did you manually install Apache, PHP or what?
PS And you have Linux, but the question remains, something with DNS most likely, try to specify a normal mailbox ...