/**
 * Right after a donation is made, this sends the donation receipt to 
 * the donor if the donation is pending AND it was made in offline mode.
 *
 * @param   int $donation_id
 * @return  boolean
 */
function en_send_donation_receipt_for_pending_offline($donation_id)
{
    /* Verify that the email is enabled. */
    if (!charitable_get_helper('emails')->is_enabled_email(Charitable_Email_Donation_Receipt::get_email_id())) {
        return false;
    }
    /* If the donation is not pending, stop here. */
    if ('charitable-pending' != get_post_status($donation_id)) {
        return false;
    }
    /* If the donation was not made with the offline payment option, stop here. */
    if ('offline' != get_post_meta($donation_id, 'donation_gateway', true)) {
        return false;
    }
    /* All three of those checks passed, so proceed with sending the email. */
    $email = new Charitable_Email_Donation_Receipt(array('donation' => new Charitable_Donation($donation_id)));
    /* Don't resend the email. */
    if ($email->is_sent_already($donation_id)) {
        return false;
    }
    $sent = $email->send();
    /* Log that the email was sent. */
    if (apply_filters('charitable_log_email_send', true, Charitable_Email_Donation_Receipt::get_email_id(), $email)) {
        $email->log($donation_id, $sent);
    }
    return true;
}