SMTP Server -> Queued in the outgoing mail

Jay, in your case why smtp is not working cause of snat configuration. Client ip needs to be preserved in this case, which offcorse is not happening as u have snat enabled. So now I can suggest you couple of ways to make it work. Make a new van, place your servers one by one if they r in clustered mode to prevent outage to your customers in this new van, default gw on these servers be the self ip of ltm, no snat configuration, that's all. In case if Two arm configuration is not going easy for you, Then staying in one arm you can take advantages of smtp proxy irule to inject and modify the clear text protocol smtp to preserve the original source. Your post looks like a week old, let me know if it's resolved by now

-- ravi k. Malhotra --