winbindd: how to get rid of DOMAIN part for authentification?

[Andreas Schuldei]

I set up winbind and it works fine. I can log in to my samba box with
ssh and friends like this: DOMAIN+joe.user, and then give his
password.

But people are not used to that. They want to log in with joe.user and
their password, and that is it. In fact we only have one seriously
used domain. How can I configure my samba box to accept those shorter
logins?