These are the entries I have in my local domains:

192.168.0.25 / amelia.oldrivercabinets.com
192.168.0.25 / amelia
192.168.0.25 [192.168.0.25]
192.168.0.25 [69.131.61.182]
192.168.0.25 [69.131.61.142]

Why the / in front of the domains?  This makes all mail to  anyuser@amelia.oldrivercabinets.com non-local mail.  BTW, when showing the domains it's best to simply post the [Domains] section of the mercury.ini file.

This is the Postfix program at host mxout-03.mxes.net.

I'm sorry to have to inform you that your message could not be
delivered to one or more recipients.  Here is the reason why the
message could not be delivered.

<maw@amelia.oldrivercabinets.com>: host
    amelia.oldrivercabinets.com[69.131.61.182] said: 553 We do not relay    non-local mail, sorry. (in reply to RCPT TO command)

These are the entries I have in my local domains:

192.168.0.25 / amelia.oldrivercabinets.com
192.168.0.25 / amelia
192.168.0.25 [192.168.0.25]
192.168.0.25 [69.131.61.182]
192.168.0.25 [69.131.61.142]

Any Ideas?!?! 

Sending test messages from the File menu also returns 553 relaying not allowed :(

Tue 26, 14:04:26: Job MG00000C: from postmaster@ameila.oldrivercabinets.com (local)
   Created outgoing job with ID MO00000D
   To: maw@amelia.oldrivercabinets.com (non-local) -OK

*sigh*