<?php

date_default_timezone_set('Europe/Moscow');
require 'phpMailer/PHPMailerAutoload.php';

$mail = new PHPMailer;

$mail->IsSMTP();
$mail->Host = 'smtp.gmail.com';
$mail->SMTPAuth = true;
$mail->SMTPSecure = 'ssl';
$mail->Port = 465;
$mail->CharSet = 'UTF-8';

$body = file_get_contents('content.html');
$mail->Username = 'xxxxxx@gmail.com';
$mail->Password = 'xxxxxx';
$mail->SetFrom('xxxxx@gmail.com', 'xxx');
$mail->Subject = 'Отправка письма с GMAIL';
$mail->MsgHTML($body);
$address = 'xxxxx@gmail.com';
$mail->AddAddress($address,'to_xxxx');

if($mail->Send()){
    echo 'Письмо отправлено';
}else{
    echo $mail->ErrorInfo;
}


?>

SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting