The rule of HL7 is that the sender should resend a message if it has not been ACKnowledged by the receiver. If the application that is sending messages to you is correctly implemented and is sending messages asynchronously, you could get away without doing any persistent queuing, which would remove a bottleneck in your process.

However, the norm for most HL7 asynchronous applications is that they are not correctly implemented and a translator needs to assume responsibility for storing and forwarding messages (queueing persistently).