Why is my computer sending emails

I am currently using Debian Squeeze 6.0. The administrator of my work place receives every week messages from several processes of my system:

• cron
• smartd
• ...

The messages are send to [email protected]. I suspect that the mail should be send to root@localhost or something, but I think some redirection is done somewhere.

Thanks

EDIT:

echo "test" | mail root -s "this is a test"

cat /var/log/mail.log
Apr 30 14:23:38 yavapai nullmailer[3020]: Trigger pulled.
Apr 30 14:23:38 yavapai nullmailer[3020]: Rescanning queue.
Apr 30 14:23:38 yavapai nullmailer[3020]: Starting delivery: protocol: smtp host: mail.domain.fr file: 1241094218.13394
Apr 30 14:23:39 yavapai nullmailer[13395]: smtp: Succeeded: 250 2.0.0 n3UCNdZq025564 Message accepted for delivery
Apr 30 14:23:39 yavapai nullmailer[3020]: Sent file.
Apr 30 14:23:39 yavapai nullmailer[3020]: Delivery complete, 0 message(s) remain.
Apr 30 14:23:39 yavapai nullmailer[3020]: Trigger pulled.
Apr 30 14:23:39 yavapai nullmailer[3020]: Rescanning queue.

Check /etc/aliases, look for the line

root: [email protected]

edit: as a test, try this

echo "test" | mail root -s "this is a test"

then check /var/log/maillog, and the headers when it is received on your admins machine

I imagine that Dave is right and your issue is with /etc/aliases, but FWIW, you can set cron output to go to a specific address by putting a MAILTO line at the top. Run crontab -e and add something like [email protected] as the first line. Note that this will go through the regular email system you have installed, which presumably includes any /etc/aliases changes.

Did you set your hostname correctly?