domain alias question

[I . Herman]

OK....i finally got everything running..thanks to all that helped.

Now..here's the next question:

I am hosting my domain, madhorizons.com which is an alias of madart.myip.org.

If i send to [EMAIL PROTECTED] it gets here w/ no problem.  But when I 
reply, it changes things to [EMAIL PROTECTED]  how do i get qmail to keep 
the aliased domain in the address?