Setting WindowSize=0 is current invalid. Setting WindowSize=1 (currently the option for slow consumers I found on cdoe), will of course keep at least one message on the buffer. I have added a testSlowconsumer validating it with WindowSize=1 as it doesn't work with WindowSize=0 ATM (It would need some dev around that). I thought there was a JIRA somewhere for that but i couldn't find it now. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4221420#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...