[ubuntu] local mail does not work

[doru001]

Local mail, between two users (root and user) on one Ubuntu machine, does not work.
I am using mailx as MUA and postfix as MTA. I followed these instructions:
https://help.ubuntu.com/community/Postfix
The test worked.

I see errors in /var/log/mail.info:
postfix/error[8785]: BA64315F9C: to=<root@127.0.0.1>, relay=none, delay=0.32, delays=0.09/0.12/0/0.11, dsn=5.1.3, status=bounced (bad address syntax)

root has no mailbox:
# ll /var/mail
total 0
-rw-rw---- 1 user mail 0 2009-09-14 12:23 user
# cat /etc/aliases
# See man 5 aliases for format
postmaster: root
# Added by installer for initial user
root: user

https://help.ubuntu.com/community/Postfix
says that I should configure mailx to use ~/mail as mailbox, but I found no way to do that.

I believe I have installed Ubuntu with full mail server, like gcornett here: http://ubuntuforums.org/showthread.php?t=1041665&highlight=mailx+local
The solution gcornett has applied, to reinstall the system with local mail server, is not attractive. I messed up with dpkg-reconfigure postfix and with /etc/postfix/main.cf several times, but in vain.

I have found the following similar cases:
http://www.experts-exchange.com/OS/L..._22502033.html
http://www.experts-exchange.com/OS/L..._24172709.html

Please post the main.cf and /etc/mail.rc of a working system.
Any information that would help me find my way around is welcomed.

[doru001]

To summarize:

1. It seems that, when one installs Ubuntu server with Internet mail server included, local mail does not work, not to mention Internet mail. When one installs Ubuntu server with local mail server included, local mail works.
2. Nobody bothered to confirm or contradict the above statement, using their own installation configuration. All one has to do is to:
mail user
some test email between two local users, text mode.
3. Nobody bothered to post his configuration files, /etc/postfix/main.cf and /etc/mail.rc, from a system where local mail works. This would possibly help me avoid reinstall.