//215delete_sentmail_monthly_keep
// how many old sent-mail folders to keep every month?
$_prefs['delete_sentmail_monthly_keep'] = array(
    'value' => 12,
    'locked' => false,
    'shared' => false,
    'type' => 'number',
    'desc' => _("Number of old sent-mail folders to keep if deleting monthly."),
    'help' => 'prefs-delete_sentmail_monthly_keep');
