I am seeing basically the same issue as the original poster - however, I can find no solution. -I am using multiple Solaris 8 platforms with older hardware. -I have experienced the problem on both jboss v4.0.5GA and v4.2.2GA. -I am using a default jboss configuration with the one exception that I have altered it to use an mysql backend. In my situation I have multiple servers involved in the messages lifespan but I do not use any clustering and I have only one poster/consumer on any one Queue at any time. Senerio: 1. Each message contains a unique (sequential) serial number in its body. 2. Messages are written to a JMS Queue "A" on server #1 at around 200 millisecond intervals. 3. Messages are read from the Queue "A" manipulated and sent thru other servers using ordinary TCP sockets. The destination server writes the resulting message back to a new JMS Queue "B" on server #5. 4. Final application is sitting in an infinite loop reading messages as fast as it can from Queue "B" with CLIENT_ACKNOWLEDGE set and using 'receive(2000)' - Note: 2 second timeout. Each message that is read is acknowledged then the unique serial number is parsed from the message contents and compared to previously received messages. I always receive about a half a dozen messages out of order in a 300-350 thousand message set. The unique serial number stays consistently in sync with the JMS Message ID that is stored in the message header. This implies that the messages are written to the JMS Queue "B" in the correct order. It is only when I read them back that they become out of order. Normally, an out of order message will only be off by one message. However, I have had examples where a message is actually retrieved 5 messages late ( roughly a second late ). Between the unique serial number in the message body and the JMS Message ID and logging that I perform on the sending side I am confident that the messages are being written in order. I have to be able to say(guarantee) that we can deliver message in a FIFO order. I can not find any comments or postings suggestion that anyone has a fix for this. I know current development is geared toward Jboss v5 and Jboss Messaging versus JbossMQ, but I need to find a fix for this! What can I do? Do you have any suggestions? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4109386#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...