MassTransit Endpoints (IEndpoint) are an abstraction layer on top of the actual transport. So in the case of MSMQ the endpoint represents an MSMQ Queue. Endpoints are constructed using the IEndpointFactory and are done so with a URI (like msmq://servername/private_queue_name).

For MSMQ queues, you can provide a hint in the query string for the transactional status of a queue. The default is that remote queues are transactional and local queues are non-transactional (but local queues can be queried). To signify a non-transactional remote queue it's msmq://remote_host/mt_subscriptions?tx=false.