[Mailman-Users] Problems with local network: mailman 2.1.5 + Sendmail

[MJ Roxas]

Hi guys, i'm having some problems with this configuration: local network
I've configured mm_cfg.py just adding:
DEFAULT_URL_HOST  
= fqdn 

DEFAULT_EMAIL_HOST = fqdn

DELIVERY_MODULE = 'Sendmail'
I've set mmsite pass and created the newlist called mailman.Also i've created another list so as to test, and i've added two members to them (i can see in files that all of this is correct).I've putted new aliases in /etc/aliasesSendmail lets me send and receive local mail (i can see it in /var/spool/mail).
The problem is when i try to post something to the list.
Where does Mailman get this mail?How send it to the rest of the members? 
Sorry for my beginner questionThank!