I am having problems with sending emails with gmail accounts that require authentication. I am getting the following error:

PROBLEMS SENDING MAIL TO xxxx@xxxx.com Mailer Error: The following From Addres failed: xxxx@xxxx.com: MAIL FROM command failed, 530,5.5.1 Authentication required. Learn more at 530 5.5.1 http://support.google.com/mail/bin/answer.py?answer=14257 m6sm3438166qai.13 - gsmtp

I saw in the forums mantis similar errors but I could not fix it. I configured my config_inc.php file as follows:

<?php
$g_hostname = 'localhost';
$g_db_type = 'mysql';
$g_database_name = 'MantisDB';
$g_db_username = 'root';
$g_db_password = 'xxxx';

# E-Mail addresses
$g_smtp_connection_mode = 'ssl';
$g_administrator_email = 'xxxx@xxxx.com';
$g_webmaster_email = 'xxxx@xxxx.com';
$g_from_email = 'xxxx@xxxx.com'; # Puede ser inventando
$g_return_path_email = 'xxxx@xxxx.com';
$g_phpMailer_method = 2; # 0 - mail(), 1 - sendmail 2 - SMTP
$g_smtp_host = 'smtp.gmail.com';
$g_smtp_port = 465;
$g_smtp_username = 'xxxx@xxxx.com';
$g_smtp_password = 'xxxxx';

?>

Could you help me fix it?