Why is wordpress form not submitting?

Question

PHP

After filling out the form on this page , the entered data should be displayed to the user and sent to the mail.
They are displayed on the screen, from which I concluded that all variables were processed normally, but I cannot understand why the data is not sent, maybe someone knows what the problem is?
(From the "counters" page, when the submit button is clicked, it redirects to the mail.php page, which works thanks to the included wp-load.php)
Here is the code that "should" send data, but does not :(

<?php
mail( "[email protected]", "Показания счетчиков", "<h3>Показания счетчиков с адреса:</h3><b>Ул. </b>".$adres.", <b>кваритра - </b>".$room."<b> от </b>".$data_day.".".$data_month.".".$data_year."г."."<br/><br/><h3>Показания счетчика электроэнергии:</h3>"."<b>Тип счетчика - </b>".$e_tarif."<br/><b>Показание - </b>".$electro."<h3>Показания счетчиков воды: </h3>"."<b>Водомер №1(Холодная) - </b>".$water1."<br/><b>Водомер №2(Горячая) - </b>".$water2."<br/><b>Водомер №3(Холодная) - </b>".$water3."<br/><b>Водомер №4(Горячая) - </b>".$water4."<h3>Данные отправителя:</h3><b>ФИО:</b> ".$fio."<br/><b>Электронная почта:</b> ".$email."<br/><b>Контактный телефон:</b> ".$phone."<h3>Дополнение отправителя:</h3><i>".$comment."</i>", "Content-type:text/html;charset=utf-8");
?>

Answer 1

Try contact form 7 plugin

Answer 2

Try wp_mail