I think this might be a vaild issue under some circumstances but there is an easy workaround. I looks like the issue with #5 is that he didn't put a space between cat and the file path. I have the same issue with a fresh install and default settings.
The issue is that for a default install, the installer grabs the full comcast domain and puts that with a trailing dot in the /etc/hosts (not sure if that's valid or not) and then by default the postfix package grabs that hostname as the mail hostname. Here is the output for me: gitad...@ubuntu:~$ postconf myhostname myhostname = ubuntu.hsd1.il.comcast.net. gitad...@ubuntu:~$ cat /etc/hosts 127.0.0.1 localhost 127.0.1.1 ubuntu.hsd1.il.comcast.net. ubuntu # The following lines are desirable for IPv6 capable hosts ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters gitad...@ubuntu:~$ cat /etc/hostname ubuntu FIX: Removing the trailing dot from the myhostname entry in /etc/postfix/main.cf fixes the issue for me. -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to postfix in ubuntu. https://bugs.launchpad.net/bugs/377571 Title: package postfix 2.5.5-1.1 failed to install/upgrade: -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs