Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail Ubuntu 8.10

[slohning]

Hi all,
I am trying to set up postfix mail as per the Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail (Ubuntu 8.10) tutorial.
I have the following error
warning: do not list domain xxxx.com in BOTH virtual_alias_domain and virtual_mailbox_domains.

This is what it sends back in email messages
This is the mail system at host daijisuanji.oxnee.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<slohning@oxnee.com> (expanded from <stephen.lohning@oxnee.com>): mail for
192.168.1.150 loops back to myself

Any one go any ideas what I am doing wrong?