Question : internal send to domain alias refused

I have an exchange server 2007 sp1 with multiple domain wide aliases. If I send to the mail server from outside the network I can use user@domainx.com, user@domainaliasy.com and user@domainaliasz.com without a problem.

However, when inside the network I can only send to the default domain user@damainx.com, if I mail from inside to user@domainaliasy.com I recieve the following response:

Diagnostic information for administrators:

Generating server: AMI.aesd.net

user@domainaliasy.com
#550 5.1.1 RESOLVER.ADR.RecipNotFound; not found ##

Original message headers:

Received: from sysdamin3 (10.0.0.1) by mail.domainx.com(192.168.1.1) with
 Microsoft SMTP Server id 8.1.240.5; Mon, 3 Nov 2008 09:18:12 -0800
Message-ID: <23079E65DCEE4603B37DC65E355F40A3@aesd.net>
From: user
To:
Subject: Blah Is Alias
Date: Mon, 3 Nov 2008 09:18:13 -0800
Organization: Our Organization
MIME-Version: 1.0
Content-Type: multipart/alternative;
      boundary="----=_NextPart_000_0022_01C93D95.18CB06F0"
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 6.00.2900.5512
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579
Return-Path: user@domainx.com

Answer : internal send to domain alias refused

Solved it myself,
In the E-Mail Address Policies, the alias domains were not listed,

%m@domainaliasy.com
%m@domianaliasz.com

Under the email addresses dialog, even though they were in the accepted domains list.