A few things; for one please fix your /etc/hosts as it is incorrect
Code:
127.0.0.1 localhost.localdomain localhost
your.ip.address FQDN yourhostname
Secondly you have your FQDN as demo.mydomain.net yet the MX record points to mail.demo.mydomain.net ? Your server FQDN should be mail.demo.mydomain.net in /etc/hosts.
And why have you put all the output in a attachment ? Just post it all under a code section as it makes it easier for us to reply and especially quote sections.