Preserving Client IP address for SMTP traffic

Hi I'm facing the same problem as what Ray Sbrusch described, and I couldn't find a solution. I need the smtp server to see the actual client IP (at the same time traffic being loadbalanced) instead of the SNAT VIP so I can do accounting. Seems after I disable the SNAT, the loadbalancer doesn't even send the traffic to the SMTP server as I can't see any connection from actual client in the smtp monitoring page. I understand I can do a IP forwarding but that'll disable the laodbalancing.