Linux – Get postfix to forward root’s mail

I have an Ubuntu server running postfix. It is not the mail server for my domain.

Whenever a cron job runs for root, the output mail is not delivered locally, instead it gets sent to root@mydomain.com via the main mail server. This is not what I want.

I want mail for root to either be delivered locally or forwarded to anothermail@anotherdomain.com.

I've tried modifying both ~root/.forward and /etc/aliases (and running newaliases), but nothing helps (I guess these files are only checked when postfix tries to deliver mail locally).

What can I do?

This is /etc/postfix/main.cf:

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
append_dot_mydomain = no
readme_directory = no
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
myhostname = linux1.mydomain.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = linux1.mydomain.com, localhost.linux1.mydomain.com, localhost
relayhost = my.isps.relayhost.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = loopback-only

Edit:

When sending mail to root, this goes into /var/log/mail.log:

Mar  7 09:39:17 linux1 postfix/pickup[31381]: F3B9C98025E: uid=1000 from=<ct>
Mar  7 09:39:18 linux1 postfix/cleanup[31556]: F3B9C98025E: message-id=<20130307083917.F3B9C98025E@linux1.mydomain.com>
Mar  7 09:39:18 linux1 postfix/qmgr[28525]: F3B9C98025E: from=<ct@mydomain.com>, size=283, nrcpt=1 (queue active)
Mar  7 09:39:18 linux1 postfix/smtp[31558]: F3B9C98025E: to=<root@mydomain.com>, orig_to=<root>, relay=my.isps.relayhost.com[<IP address omitted>]:25, delay=0.72, delays=0.19/0.02/0.27/0.25, dsn=2.0.0, status=sent (250 Ok: queued as A97F5D8126)
Mar  7 09:39:18 linux1 postfix/qmgr[28525]: F3B9C98025E: removed

The name "ct" is my user name. I generated the above text through this command:

echo test | mail -s test root

The content of /etc/mailname is:

mydomain.com

The contents of /etc/aliases is:

root: anothermail@anotherdomain.com
postmaster:    root

where anothermail@anotherdomain.com is where I would like root's mail to be forwarded to.

The content of /etc/hosts actually surprises me a little:

127.0.0.1 localhost
127.0.1.1 linux1.mylinux.mydomain.com linux1

where "mylinux" is the hostname of a host operating system under which linux1 runs as a virtual machine. I'm not sure how "mylinux" got in there. (But could this really be the reason for my problem?)