The JBM core api is more powerful than the JMS API in that if you call message.acknowledge() it will acknowledge all messages up to and including that one that have been delivered on the session. This differs from the JMS message.acknowledge() which acknowledges *all* messages that have been delivered on that session up until the time when you call it. There is a subtle but important difference there. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4247592#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...