[imp] not receiving error notifications

[TN]

When using IMP, I don't receive any error notifications such as 
undeliverable notifications etc.
This is because there is a received path between the browser and the 
server, which is like this:

Received: from www-data by box.mydomain.com with local (Exim 4.30)
	id 1BAjXp-0000Sp-PZ
	for friend at someotherdomain.com; Tue, 06 Apr 2004 15:54:45 +1000
Received: from myipaddress.somedomain.com (myipaddress.somedomain.com [23.34.86.55]) 
	by box.mydomain.com (IMP) with HTTP 
	for <me at mydomain.com@localhost>; Tue,  6 Apr 2004 15:54:45 +1000
...
...
...
User-Agent: Internet Messaging Program (IMP) 3.2.2
Sender: www-data <www-data at box.mydomain.com>


So what happens is that error emails are sent to 
www-data at box.mydomain.com instead of me at mydomain.com (I found this by 
checking the incoming logs)

I tried looking in IMP for where it sets the "Sender: www-data 
<www-data at box.mydomain.com>" field, but I can't find it.

Does someone know how to fix this ?
I am using cyrus & horde2, and virtdomains in cyrus, so my user accounts 
are all like me at mydomain.com


-Trevor