>The spam-assassin filter is still on testing period so some messages are >marked as SPAM only but are not blocked. Could that be the reason of >duplicated emails?
Possibly a problem with SA. If you remove it does the problem go away? Also think about how spam assassin is configured. If you are like most people it goes MTA -> postqueue (SA) -> MTA. So, if you are running the basic run of the mill SA you are re-injecting the email into the system on local, which is why you are seeing the entries twice. I assume there is more to the log file that you aren't including (like the MTA connection? If you look at it, you are probably getting an external connection, accepting it, processing it, handing it to SA, then you will see a connection from localhost, accepting it, processing it, forwarding it on (or delivering local). Are you seeing this in your logs?
