jan4971 on "Problem with user_mail in functions.php"

Hey guys, i have some issues with this thing here:

add_shortcode('authors-list', 'my_authors_list_shortcode');
function my_authors_list_shortcode( $atts = array() ) {
    global $wpdb;
    $users = $wpdb->get_results( "SELECT ID, display_name FROM {$wpdb->users}" );

    $content = "<ul class='authors-list'>";
    foreach( $users as $user ) {
        $content .= "<li>";
        $content .= get_avatar( $user->ID, 70 );
        $content .= "<h3>" . $user->display_name . "</h3>";
        $content .= "<p class='author-description'>" . get_user_meta( $user->ID, 'description', true ) . "</p>";
        $content .= "<p class='author-description'>" . get_user_meta( $user->ID, 'phone', true ) . "</p>";
        $content .= "<p class='author-description'>" . get_user_meta( $user->ID, 'livingplace', true ) . "</p>";
		$content .= "<p class='author-description'>" . $current_user->user_email . "</p>";
		$content .= "</li>";
    }
    $content .= "</ul>";
    return $content;
}

It seems like there is no way to output all users email adresses.
Any one got an idea ?