<?php

//....

$pass = 'qwertyqwerty';

//$row['user_mail'] = 'wans@localhost';
//$row['id_user'] = 1;

$link = 'http://elink.kz/respass/reset/code/'.md5($pass).'/'.$row['id_user'];


$from    = '<register@elink.kz>';
$to      = '<'. $row['user_mail'] .'>';
$subject = base64_encode('Изменить пароль');

$message ='текст текст: '.$link;

// To send HTML mail, the Content-type header must be set
$headers[] = 'MIME-Version: 1.0';
$headers[] = 'Content-type: text/html; charset="UTF-8"';

// Additional headers
$headers[] = 'To: '. $to;
$headers[] = 'From: '. $from;
$headers[] = 'Reply-To: '. $from;
$headers[] = 'X-Mailer: ElinkMailer';

// Mail it
$success = mail($to, $subject, $message, implode("\r\n", $headers));

if (!$success) {
    $errorMessage = error_get_last()['message'];
}