I recently upgraded to 9.5.1 on Centos64. I upgraded because I was previously assured that when this update appeared it would fix the issues with postfix queue timeing out on large attachment (not even that large (4mbish)). I am not really surprised that this issue is not fixed as I am used to this kind of thing from Parallels, but, a bigger one has been introduced which is really causing us a problem, this new issue did not exist in 9.3 so I have upgraded into a new problem!.. If greylisting is enabled then email from one domain hosted on the server cannot be delivered to another domain hosted on the server. It seems that the server it self is not reacting correctly to it's own greylisting.