Not sure if this matters any but we do have a unique situation with this Incoming Gateway. It handles email for a Google Apps Split Delivery Mail Routing. Basically email comes into Google Apps and if it is addressed to a user that is not found at Google Apps it is delivered to our SmarterMail Incoming Gateway to be processed and routed to those users on that domain hosted by our Primary SmarterMail server. The Google Apps Servers are listed in the AntiSpam Bypass Gateways so that AntiSpam Checks skip those hops.
Maybe there is an issue in v15 with the logic that handles AntiSpam Bypass Gateways?