Wordpress smpt setting in the config file

i moved my network to hostgator. i configured my smpt setting in the config file with the following setting but it is not sending email

define('WP_SMTP_HOST', 'smtp.gmail.com');
define('WP_SMTP_PORT', 25); // obligatory - default: 25
define('WP_SMTP_ENCRYPTION', 'tls'); // obligatory: 'tls' or 'ssl' - default: no encryption
define('WP_SMTP_USER', 'username'); // obligatory - default: no user
define('WP_SMTP_PASSWORD', 'password'); // obligatory - default: no password