Thanks for the info Greg. We use a transport agent to route the mail between tenants back out so it can be filtered and have any rules applied that run on our smarthost and inbound servers. This new agent will hopefully allow us to reduce the complexity of the logic in our routing agent in deciding what messages need to be routed back out since they are inter-tenant. One minor issue that we run into with this is when we're onboarding a new tenant, once their users are created. At that point the transport agent is routing mail out to the internet but the recipients are being resolved as local and no content conversion is being applied and this happens in the transport stack before out agent can grab the message. It's a minor issue, but we had speculated that perhaps with this new agent that the message was being formatted as if it was intended for an internet recipient. Hope that makes sense. It's a tricky issue. Thanks again for the fast reply.