FC6 sendmail does not send mails from/to local users

[Christian Menzel]

Hi!

On my fresh install of FC6 sendmail is not working correctly.

When trying something like
mail -s Test root

the mail is not sent but instead I get following message:
/home/chris/dead.letter... Saved message in /home/chris/dead.letter

and in /var/log/maillog:
Nov  6 17:35:12 nomad sendmail[5023]: kA6GZC7V005023:
ruleset=check_mail, arg1=<chris at localhost.localdomain>, relay=localhost
[127.0.0.1] (may be forged), reject=553 5.5.4
<chris at localhost.localdomain>... Real domain name required for sender
address
Nov  6 17:35:12 nomad sendmail[5022]: kA6GZCZV005022: to=root,
ctladdr=chris (500/500), delay=00:00:00, xdelay=00:00:00, mailer=relay,
pri=30029, relay=[127.0.0.1] [127.0.0.1], dsn=5.6.0, stat=Data format
error
Nov  6 17:35:12 nomad sendmail[5023]: kA6GZC7V005023:
from=<chris at localhost.localdomain>, size=29, class=0, nrcpts=0,
proto=ESMTP, daemon=MTA, relay=localhost [127.0.0.1] (may be forged)

The mail is rejected because a real domain name is required.
Should I define a (faked) domain name for local mail, I didn't have this
problem on previous installs.

Regards
Chris