Steps to reproduce the issue

From back end
In Users component options have:

• allow user registration
• send password to NO In plugins->user->joomla options disable emails notification during registration.

Expected result

When a user register not to get any notification email.

Actual result

The email notification is send not matter what.

System information (as much as possible)

Joomla 3.3.6

Additional comments

The problem found to be on file:
/joomla_path/components/com_users/models/registration.php
line 502. You must change this line with below:

$user_plugin = JPluginHelper::getPlugin('user', 'joomla');
$mail_to_user = json_decode($user_plugin->params)->mail_to_user;
if ($mail_to_user) {
$return = JFactory::getMailer()->sendMail($data['mailfrom'], $data['fromname'], $data['email'], $emailSubject, $emailBody);
} else {
$return = true;
}

I will try to put the fix in Git.