[Public network] - email gets fail

[shamun]

If i send email from local box, it work, but if i send email from outside my network gets failed like google/yahoo email etc. I am using postfix/postfixadmin/dovecot for virtual domain name emails.

sending bounce, fail:
=================
Delivery to the following recipient failed permanently:

support@xxxx.be

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 5.1.1 <support@xxxxx.be>: Recipient address rejected: User unknown in virtual mailbox table (state 14).

----- Original message -----

MIME-Version: 1.0
Received: by 10.213.107.78 with SMTP id a14mr534719ebp.10.1272097991223; Sat,
24 Apr 2010 01:33:11 -0700 (PDT)
Received: by 10.213.14.18 with HTTP; Sat, 24 Apr 2010 01:33:11 -0700 (PDT)
Date: Sat, 24 Apr 2010 10:33:11 +0200
Message-ID: <x2g59375a791004240133wf3cb007dpdbb8871ad32429a6@ma il.gmail.com>
Subject: test
From: test <xxx@gmail.com>
To: support@xxxxx.be
Content-Type: multipart/alternative; boundary=00504502cc86e2ea1b0484f76492

test

[falko]

Please make sure that the MX record for your domain points to the correct server. You can check that by running
dig mx yourdomain.com

[irel]

I think you also need to modify/check postfix-config:
- backupmx = '1' and relay_domains = [your domain]