When you shut down, JBoss shouldn't deliver additional messages to your MDB. What else are you talking about?
when shutdown jboss, the server waits until jms queues are processed. We have many messages and some time this process can take more than 10 minutes(graceful shutdown). Most of the time we are obliged to force the shutdown.
We woud like to implement a kind of "graceful shutdown" when we force the shutdown.