help needed for mailman

[dinar ali kadri]

hi,

i am trying to configure mailman on fedora core 2. i made everything  
and did the aliases as well but the problem is this when i subscribe   
as a test to see if its working after that i check on smtp-failure log  
and i finds
(3959) SMTP session failure: 553, 5.3.0 <unix-bounces at pakishop.com>...  
user User unknown

so what shall i do to make unix-bounce as unix-bounce at pakishop.com in  
my aliase or i have to do some more changes ?or i missconfigured  
something please point me out .i think it should look like a local mail  
address then a masqueraded.

i know i did everything in a rush and making some silly mistake.Is  
there any one can point my mistake out and tell me where should i  
start?

thanks
bye