Ability to view messages that have been sent by email

In my application, the system sends messages to a user by email. This user also has access to the application and is able to view the messages they have received within the application.
The issue comes if the user chooses to reply to messages using the application rather than using email.
Because the original message was sent by the system, it is marked as ‘outbound’. It is therefore not possible to reply to it because LC only allows you to reply to ‘inbound’ messages.
Is there any way of sending a message so that it is ‘outbound’ when viewed by the sender, and ‘inbound’ when viewed by the recipient?