I have fress install of ubuntu 12.04 x32 and both times I had problem with installing post fix.
Even If I manually install postfix it appears the same error. I have digitalocean vps.
This is what it says
Processing triggers for libc-bin ... ldconfig deferred processing now taking place Errors were encountered while processing: postfix E: Sub-process /usr/bin/dpkg returned an error code (1) [ Thu Oct 9 14:51:55 EDT 2014 ] Unable to install nginx-custom, exit status = 100
EDIT: Solved. Bad hostname