I have a quick question that I couldn't find anywhere... I need a feature in postfix that doesn't seem available until 2.7. The feature is "sender_dependent_default_transport_maps". I am a small web host provider looking to provide users with dedicated IP's that they can whitelist to improve email deliverability and so they control their own reputation. This url describes what I want to do basically: http://www.zoobey.com/index.php?option=com_content&view=article&id=260 My real question is this: Can I update postfix to 2.7 without breaking anything in ispconfig? IE. After I update would the users be able to setup new emails, etc, with no problems? Are all the config files the same, etc? If it's possible, what's the easiest way to do so? Build it from source? Find an RPM? Thanks in advance for any help/insight into this issue and if you have other better suggestions for what I'm looking to do those would be greatly appreciated as well!