<?php
add_action('admin_menu', 'ds_emails_all_add_menu');

function ds_emails_all_add_menu()
{
	if (is_super_admin())
	{
		add_submenu_page('ms-admin.php', 'Email All', 'Email All', 'manage_network', 'email_all', 'ds_emails_all_page');
	}
}

function ds_emails_all_page()
{
if( is_super_admin() == false ) {
	wp_die( __('You do not have permission to access this page.') );
}
?>
<div class='wrap'>
<h2>Email All</h2>
<p>Following is a list of email addresses that are administrators of one or more blogs on this WPMU installation.</p>
<pre>
<?php
global $wpdb;

$query = "SELECT DISTINCT (u.user_email) FROM $wpdb->usermeta m INNER JOIN $wpdb->users u on m.user_id=u.id WHERE meta_key like 'wp_%_user_level' and meta_value='10' ORDER BY 1";

//$query = "SELECT DISTINCT user_email FROM $wpdb->users ORDER BY user_email ASC"; //all users

$emails = $wpdb->get_results($query);

foreach ($emails as $e) {
	echo "$e->user_email, \n";
}
?>
</pre>
</div>
<?php
}
?>