I don't see the "To" line being rewritten on my server. My mailbox accepts mail for several adresses and they all show up in the mails' headers. I also have an external adress that forwards mail to my local scalix account and the To-address remains unchanged in the headers, too. Same thing with mails coming from external mailing lists.
Well, I don't think I've actively turned on / off any features that would do this,b ut below is header from one test example. As you can see it was sent to accounts@ and was directed to the correct user account, but the To: field has been re-written to enquiries@ which is the defaul, ie first, email address for that user account.
[i]Return-Path: <andy@mydomain.com>
Received: from caladan.mydomain.com (localhost [127.0.0.1])
by caladan.mydomain.com (8.13.4/8.13.4/SuSE Linux 0.7) with ESMTP id k2IFihuv015163
for <accounts@mydomain.com>; Sat, 18 Mar 2006 15:44:46 GMT
Received: from caladan.mydomain.com (root@localhost)
by caladan.mydomain.com (8.13.4/8.13.4/Submit) with ESMTP id k2IFihJg015162
for <accounts@mydomain.com>; Sat, 18 Mar 2006 15:44:43 GMT
Received: from [192.168.42.17] (muadib.mydomain.com 192.168.42.17)
by caladan.mydomain.com (Scalix SMTP Relay 10.0.0.175)
via ESMTP; Sat, 18 Mar 2006 15:44:43 +0000 (GMT)
Date: Sat, 18 Mar 2006 15:38:41 +0000
From: "Andy Flisher" <andy@mydomain.com>
To: "Enquiries" <enquiries@mydomain.com>
Message-ID: <441C2981.7060809@mydomain.com>
In-Reply-To: <441C28EB.3040609@mydomain.com>
References: <441C28EB.3040609@mydomain.com>
Subject: Re: test
User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923)
X-Accept-Language: en-us, en
X-Spam-Status: No, score=-2.4 required=5.0 tests=ALL_TRUSTED autolearn=failed
version=3.0.4
X-Spam-Checker-Version: SpamAssassin 3.0.4 (2005-06-05) on caladan.mydomain.com
MIME-Version: 1.0
Content-Type: text/plain;
charset="ISO-8859-1"
Content-Disposition: inline[/]i